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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2019	Mar. 02, 2020	Jun. 30, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	Arbutus Biopharma Corp
Document Type	10-K
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		68,941,406
Entity Public Float			$ 118,248,358
Amendment Flag	false
Entity Central Index Key	0001447028
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY

Consolidated Balance Sheets - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 31,799,000	$ 36,942,000
Investments in marketable securities	59,035,000	87,675,000
Accounts receivable	1,204,000	1,431,000
Prepaid expenses and other assets	1,790,000	3,181,000
Total current assets	93,828,000	129,229,000
Investment in Genevant	0	22,224,000
Property and equipment, net of accumulated depreciation	8,676,000	10,145,000
Right of use asset	2,738,000	0
Intangible assets	0	43,836,000
Goodwill	0	22,471,000
Other Assets, Noncurrent	293,000	0
Total assets	105,535,000	227,905,000
Current liabilities:
Accounts payable and accrued liabilities	7,098,000	9,429,000
Site consolidation accrual	137,000	1,331,000
Liability-classified options	253,000	479,000
Lease liability, current	340,000	0
Total current liabilities	7,828,000	11,239,000
Liability related to sale of future royalties	18,992,000	0
Deferred rent and inducements, non-current	0	645,000
Business Combination, Contingent Consideration, Liability, Noncurrent	2,953,000	3,126,000
Lease liability, non-current	3,018,000	0
Deferred tax liability	0	12,661,000
Stockholders’ equity	32,791,000	27,671,000
Stockholders’ equity
Issued and outstanding: 1,164,000 (December 31, 2018: 1,164,000)	137,285,000	126,136,000
Issued and outstanding: 64,780,314 (December 31, 2018: 55,518,800)	898,535,000	879,405,000
Additional paid-in capital	55,246,000	48,084,000
Deficit	(970,093,000)	(805,221,000)
Accumulated other comprehensive loss	(48,229,000)	(48,170,000)
Total stockholders' equity	72,744,000	200,234,000
Total liabilities and stockholders' equity	$ 105,535,000	$ 227,905,000

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, shares authorized (in shares)	1,164,000	1,164,000
Preferred stock, no par value (in USD per share)
Preferred stock, shares issued (in shares)	1,164,000	1,164,000
Preferred stock, shares outstanding (in shares)	1,164,000	1,164,000
Common shares, no par value (in USD per share)
Common shares, shares issued (in shares)	64,789,314	55,518,800
Common shares, shares outstanding (in shares)	64,789,314	55,518,800

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenue
Total revenue	$ 6,011	$ 5,945
Non-cash royalty revenue	(1,656)	0
Operating expenses
Research and development	57,601	57,934
General and administrative	17,727	16,002
Depreciation	2,028	2,181
Site consolidation	156	4,797
Impairment of intangible assets	43,836	14,811
Impairment of goodwill	22,471	0
Legal Fees	6,266	0
Total operating expenses	150,085	95,725
Loss from operations	(144,074)	(89,780)
Other income (loss)
Interest income	2,111	3,047
Interest expense	(2,108)	(226)
Other income - Net equity investment gain or loss	(22,522)	19,322
Decrease in fair value of contingent consideration	173	7,298
Foreign exchange gains (losses)	41	(1,003)
Total other income (loss)	(22,305)	28,438
Loss before income taxes	(166,379)	(61,342)
Income tax benefit	12,656	4,282
Net loss	(153,723)	(57,060)
Items applicable to preferred shares
Dividend accretion of convertible preferred shares	(11,149)	(10,091)
Net loss attributable to common shares	$ (164,872)	$ (67,151)
Earnings Per Share, Basic and Diluted	$ (2.89)	$ (1.21)
Comprehensive income
Currency translation adjustment	$ (59)	$ 15
Comprehensive loss	(153,782)	(57,045)
Common Shares
Items applicable to preferred shares
Dividend accretion of convertible preferred shares	0	0
Net loss attributable to common shares	$ (164,872)	$ (67,151)
Earnings Per Share, Basic and Diluted	$ (2.89)	$ (1.21)
Weighted average number of common shares
Basic and diluted	57,093,454	55,304,083
Collaboration And Contracts [Member]
Revenue
Total revenue	$ 4,355	$ 5,945
OMERS
Revenue
Non-cash royalty revenue	$ 1,656

Consolidated Statement of Stockholders’ Equity - USD ($) $ in Thousands	Total	Convertible Preferred Shares	Common Shares	Additional paid-in capital	Deficit	Accumulated other comprehensive loss
Beginning balance (in shares) at Dec. 31, 2017		500,000	55,060,650
Beginning balance at Dec. 31, 2017	$ 182,473	$ 49,780	$ 876,108	$ 42,840	$ (738,070)	$ (48,185)
Issuance of Preferred Shares, net of issuance cost (in shares)		664,000
Accretion of accumulated dividends on Preferred Shares	0	$ 10,091			(10,091)
Stock-based compensation	6,687			6,687
Issuance of common shares pursuant to exercise of warrants (in shares)			0
Issuance of common shares pursuant to exercise of warrants			$ 0
Issuance of common shares pursuant to exercise of options (in shares)			458,150
Issuance of common shares pursuant to exercise of options	1,382		$ 3,297	(1,915)
Currency translation adjustment (in shares)			0
Currency translation adjustment			$ 0	0
Certain fair value adjustments to liability stock option awards	472			472
Currency translation adjustment						15
Net loss	(57,060)
Ending balance (in shares) at Dec. 31, 2018		1,164,000	55,518,800
Ending balance at Dec. 31, 2018	200,234	$ 126,136	$ 879,405	48,084	(805,221)	(48,170)
Accretion of accumulated dividends on Preferred Shares	0	$ 11,149			(11,149)
Stock-based compensation	7,204			7,204
Issuance of common shares pursuant to exercise of options (in shares)			123,282
Issuance of common shares pursuant to exercise of options	307		$ 529	(222)
Issuance of common shares			9,138,232
Issuance of common shares pursuant to our Open Market Sales Agreement			$ 18,601
Certain fair value adjustments to liability stock option awards	180			180
Currency translation adjustment	(59)					(59)
Net loss	(153,723)
Ending balance (in shares) at Dec. 31, 2019		1,164,000	64,780,314
Ending balance at Dec. 31, 2019	$ 72,744	$ 137,285	$ 898,535	$ 55,246	$ (970,093)	$ (48,229)

Consolidated Statement of Stockholders' Equity (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Statement of Stockholders' Equity [Abstract]
Issuance costs on preferred stock issued	$ 1,131

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
OPERATING ACTIVITIES
Net loss for the period	$ (153,723)	$ (57,060)
Items not involving cash:
Deferred income tax benefit	(12,661)	(4,282)
Depreciation	2,028	2,181
Loss (gain) on sale of property and equipment	20	(26)
Stock-based compensation expense	6,799	6,241
Unrealized foreign exchange (gains) losses	(68)	1,003
Change in fair value of contingent consideration	(173)	(7,298)
Impairment of intangible assets	43,836	14,811
Impairment of goodwill	22,471	0
Site consolidation non-cash portion	0	396
Net equity investment gain or loss	(22,522)	19,557
Non-cash royalty revenue	(1,656)	0
Non-cash interest expense	2,099	0
Net accretion and amortization of investments in marketable securities	(275)	0
Net change in non-cash operating items:
Accounts receivable	227	(1,029)
Accrued revenue	0	128
Investment tax credits receivable	0	(49)
Prepaid expenses and other assets	1,606	(648)
Accounts payable and accrued liabilities	(2,410)	(1,266)
Deferred revenue	0	(2,742)
Site consolidation accrual	(983)	1,331
Other liabilities	(665)	0
Net cash used in operating activities	(71,006)	(67,866)
INVESTING ACTIVITIES
Acquisition of investments	58,759	121,580
Disposition of investments	87,675	118,566
Proceeds from sale of property and equipment	11	25
Acquisition of investments	(589)	(1,138)
Disposition of investments	28,338	(4,127)
FINANCING ACTIVITIES
Proceeds from the sale of future royalties	18,549	0
Promissory note repayment	0	(12,001)
Proceeds from sale of Preferred Shares, net of issuance costs	0	66,265
Issuance of common shares pursuant to exercise of options	307	1,382
Issuance of common shares pursuant to Open Market Sales Agreement	18,601	0
Net cash provided by financing activities	37,457	55,646
Effect of foreign exchange rate changes on cash and cash equivalents	68	(1,003)
Decrease in cash and cash equivalents	(5,143)	(17,350)
Cash and cash equivalents, beginning of period	36,942	54,292
Cash and cash equivalents, end of period	31,799	36,942
Supplemental cash flow information
Preferred shares dividends accrued	(11,149)	(10,091)
Initial investment in Genevant	0	27,377
Interest Paid, Excluding Capitalized Interest, Operating Activities	0	104
Increase (Decrease) In Fair Value Of Contingent Consideration Liability	$ (173)	$ (7,298)

Nature of Business and Future Operations

12 Months Ended

Dec. 31, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of business and future operations

Arbutus Biopharma Corporation (the “Company” or “Arbutus”) is a biopharmaceutical business dedicated to discovering developing, and commercializing a cure for patients suffering from chronic hepatitis B infection, a disease of the liver caused by the hepatitis B virus (“HBV”). To pursue our strategy of developing a treatment for chronic HBV, we are developing a diverse product pipeline consisting of multiple drug candidates with complementary mechanisms of action, which have the potential to improve upon the SOC and contribute to a curative combination regimen. Our pipeline includes agents that have the potential to form an effective proprietary combination therapy.

The Company’s pipeline includes:


•	AB-729, a subcutaneously-delivered RNA interference (“RNAi”) therapeutic product candidate currently in a Phase 1a/1b clinical trial with preliminary results anticipated in late March 2020;


•	AB-836, a next-generation capsid inhibitor product candidate currently advancing through IND-enabling studies; and


•	other compounds early in the development process, including back-up capsid inhibitors, next-generation oral HBV RNA destabilizers and compounds that inhibit PD-L1.

The success of the Company is dependent on obtaining the necessary regulatory approvals to bring its products to market and achieve profitable operations. The Company’s research and development activities and commercialization of its products are dependent on its ability to successfully complete these activities and to obtain adequate financing through a combination of financing activities and operations. It is not possible to predict either the outcome of the Company’s existing or future research and development programs or the Company’s ability to continue to fund these programs in the future.

Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Significant accounting policies

Basis of presentation and principles of consolidation

Tekmira Pharmaceuticals Corporation (“Tekmira”) was incorporated in Canada on October 6, 2005 as an inactive wholly-owned subsidiary of Inex Pharmaceuticals Corporation (“Inex”). Pursuant to a “Plan of Arrangement” effective April 30, 2007, the business and substantially all of the assets and liabilities of Inex were transferred to Tekmira.

On March 4, 2015, Tekmira completed a business combination pursuant to which OnCore Biopharma, Inc. (“OnCore”), became a wholly-owned subsidiary of Tekmira.

On July 31, 2015, Tekmira changed its corporate name to Arbutus Biopharma Corporation and OnCore changed its corporate name to Arbutus Biopharma, Inc. (“Arbutus Inc.”).

The Company has two wholly-owned subsidiaries as of December 31, 2019: Arbutus Inc. and Arbutus Biopharma US Holdings, Inc., which was formed in 2018.

Protiva Biotherapeutics Inc. (“Protiva”) was acquired by the Company on May 30, 2008. On January 1, 2018, Protiva was amalgamated with Arbutus Biopharma Corporation. The Company’s former wholly-owned subsidiary, Protiva Agricultural Development Company Inc (“PADCo”) was previously recorded by the Company using the equity method. On March 4, 2016, Monsanto Company exercised its option to acquire 100% of the outstanding shares of PADCo.

These consolidated financial statements include the accounts of the Company and its two wholly-owned subsidiaries, in accordance with U.S. generally accepted accounting principles (“GAAP”). All intercompany balances and transactions have been eliminated. Certain prior year amounts have been reclassified to conform to the current year presentation.

Foreign currency translation and functional currency conversion

The Company’s functional currency is the United States dollar. Monetary assets and liabilities denominated in foreign currencies are translated into United States dollars using exchange rates in effect at the balance sheet date. Opening balances related to non-monetary assets and liabilities are based on prior period translated amounts, and non-monetary assets and non-monetary liabilities are translated at the approximate exchange rate prevailing at the date of the transaction. Revenue and expense transactions are translated at the approximate exchange rate in effect at the time of the transaction. Foreign exchange gains and losses are included in the statement of operations and comprehensive loss as foreign exchange gains.

Use of estimates

The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions about future events that affect the reported amounts of assets, liabilities, revenue, expenses and contingent liabilities as of the end or during the reporting period. Actual results could significantly differ from those estimates. Significant areas requiring the use of management estimates relate to valuation of intangible assets and goodwill, stock-based compensation, and the amounts recorded as accrued liabilities, contingent consideration, and income tax recovery.

Cash and cash equivalents

Cash and cash equivalents are all highly liquid instruments with an original maturity of three months or less when purchased. Cash equivalents are recorded at cost plus accrued interest. The carrying value of these cash equivalents approximates their fair value.

Investments in marketable securities

The Company’s short-term investments consist of marketable securities that have original maturities exceeding three months and remaining maturities of less than one year. These investments are accounted for as available-for-sale securities and are reported at fair value, with unrealized gains and losses reported in other comprehensive loss, until their disposition. Realized gains and losses from the sale of marketable securities, if any, are calculated using the specific-identification method, and are recorded as a component of other income or loss. The Company reviews its available-for-sale securities at each period end to determine if they remain available-for-sale based on the Company’s current intent and ability to sell the security if it is required to do so. Declines in value judged to be other-than-temporary are included in interest income or expense in the Company’s statements of operations and comprehensive loss. As of December 31, 2019, the recorded value of the Company’s investments in marketable securities was deemed to be recoverable in all respects.

All investments are governed by the Company’s Investment Policy approved by the Company’s board of directors.

Equity method investment

The Company accounts for its investment in Genevant Sciences Ltd. (“Genevant”) in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 323, Investments - Equity Method and Joint Ventures (“ASC 323”). In accordance with ASC 323, associated companies are accounted for as equity method investments if the Company can exercise significant influence over the associated companies. Investments in and advances to Genevant are presented on a one-line basis in the caption “Investment in Genevant” in the Company’s consolidated balance sheets, net of allowance for losses, which represents the Company’s best estimate of probable losses inherent in such assets. The Company’s proportionate share of Genevant’s net income or loss is presented along with any other gains or losses associated with the investment on a one-line basis in the Company’s consolidated statement of operations. Transactions between the Company and any associated companies are eliminated on a basis proportional to the Company’s ownership interest. The Company’s proportionate share of Genevant’s financial results are recorded on a one-quarter lag basis.

As of December 31, 2019, recovery of the Company’s remaining carrying value in Genevant was uncertain, and therefore the Company recorded a $7.6 million impairment expense to reduce the carrying value of its investment in Genevant to zero.

Property and equipment

Property and equipment is recorded at cost less impairment losses, accumulated depreciation, related government grants and investment tax credits. The Company records depreciation using the straight-line method over the estimated useful lives of the capital assets as follows:



	Useful Life (Years)
Laboratory equipment		5
Computer and office equipment	2	to	5
Furniture and fixtures		5

Leasehold improvements are depreciated over their estimated useful lives but in no case longer than the lease term, except where lease renewal is reasonably assured.

Property and equipment is reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. If such a review should indicate that the carrying amount of long-lived assets is not recoverable, then such assets are written down to their fair values.

Goodwill and intangible assets

The balances related to acquired in-process research and development (“IPR&D”) intangible assets related to the Company’s covalently closed circular DNA (“cccDNA”) program. During 2019, the Company recorded a $43.8 million non-cash impairment expense to reduce the carrying value of its IPR&D intangible assets to zero. The Company also recognized a corresponding income tax benefit of $12.7 million related to the decrease in its deferred tax liability related to the IPR&D intangible assets. The impairment was due to a decision to delay indefinitely the further development of the Company’s cccDNA program while the Company focuses on its other development programs.

The Company’s goodwill balance represented the excess of purchase price over the value assigned to the net tangible and identifiable intangible assets in connection with the business combination that formed Arbutus. During 2019, the Company assessed its changes in circumstances to determine if it was more likely than not that the fair value of its single reporting unit was below its carrying amount. Due to a sustained decrease in the Company’s share price in recent months, the Company’s market capitalization was reduced below the book value of its net assets and the Company concluded that the fair value of its single reporting unit was below its carrying amount by an amount in excess of the carrying value of the goodwill. As a result, the Company recorded a $22.5 million non-cash impairment expense to reduce the carrying value of its goodwill asset to zero.

The costs incurred in establishing and maintaining patents for intellectual property developed internally are expensed in the period incurred.

Revenue recognition

ASC 606, Revenue From Contracts with Customers (“ASC 606”) became effective for the Company on January 1, 2018, and was adopted using the modified retrospective method under which previously presented financial statements are not restated and the cumulative effect of adopting ASC 606 on contracts in process is recognized by an adjustment to retained earnings at the effective date. The adoption of ASC 606 did not change recognized revenue under the Company’s ongoing significant collaboration and license agreements and no cumulative effect adjustment was required.

ASC 606 requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers under a five-step model: (i) identify contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when or as a performance obligation is satisfied.

The Company generates revenue primarily through collaboration agreements and license agreements. Such agreements may require the Company to deliver various rights and/or services, including intellectual property rights or licenses and research and development services. Under such agreements, the Company is generally eligible to receive non-refundable upfront payments, funding for research and development services, milestone payments, and royalties.

In contracts where the Company has more than one performance obligation to provide its customer with goods or services, each performance obligation is evaluated to determine whether it is distinct based on whether (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available and (ii) the good or service is separately identifiable from other promises in the contract. The consideration under the contract is then allocated between the distinct performance obligations based on their respective relative stand-alone selling prices. The estimated stand-alone selling price of each deliverable reflects the Company’s best estimate of what the selling price would be if the deliverable was regularly sold on a stand-alone basis and is determined by reference to market rates for the good or service when sold to others or by using an adjusted market assessment approach if the selling price on a stand-alone basis is not available.

The consideration allocated to each distinct performance obligation is recognized as revenue when control is transferred to the customer for the related goods or services. Consideration associated with at-risk substantive performance milestones, including sales-based milestones, is recognized as revenue when it is probable that a significant reversal of the cumulative revenue recognized will not occur. Sales-based royalties received in connection with licenses of intellectual property are subject to a specific exception in the revenue standards, whereby the consideration is not included in the transaction price and recognized in revenue until the customer’s subsequent sales or usages occur.

Leases

As of January 1, 2019, the Company adopted FASB’s Accounting Standards Update 2016-02, Leases (ASC 842), which generally requires the recognition of operating and financing lease liabilities with corresponding right-of-use assets on the balance sheet. The Company adopted the new standard using the modified retrospective basis applied at the effective date of the new standard and elected to utilize a package of practical expedients. See note 6 for more information.

Research and development costs

Research and development costs, including acquired in-process research and development expenses for which there is no alternative future use, are charged as an expense in the period in which they are incurred.

Net loss attributable to common shareholders per share

The Company follows the two-class method when computing net loss attributable to common shareholders per share as the Company has issued Series A participating convertible preferred shares (“Preferred Shares”), as further described in note 15, that meet the definition of participating securities. The Company’s Preferred Shares entitle the holders to participate in dividends but do not require the holders to participate in losses of the Company. Accordingly, if the Company reports a net loss attributable to holders of the Company’s common shares, net losses are not allocated to holders of the Preferred Shares.

Net loss attributable to common shareholders per share is calculated based on the weighted average number of common shares outstanding. Diluted net loss attributable to common shareholders per share does not differ from basic net loss attributable to common shareholders per share for the years ended December 31, 2019 and 2018, since the effect of the Company’s stock options is anti-dilutive. For the year ended December 31, 2019, potential common shares of 8.9 million pertaining to stock options outstanding and approximately 19.4 million pertaining to if-converted preferred shares for a total of approximately 28.4 million shares were excluded from the calculation of net loss attributable to common shareholders, per share because their inclusion would be anti-dilutive. A total of approximately 24.7 million potential common shares and if-converted preferred shares were excluded from the calculation for the year ended December 31, 2018.

The following table sets out the computation of basic and diluted net loss attributable to common shareholders per share:



	For the year ended December 31,
	2019			2018
	(in thousands, except share and per share amounts)
Numerator:
Allocation of distributable earnings	$	—		$	—
Allocation of undistributable loss	(164,872		)	(67,151		)
Allocation of net loss attributed to common shareholders	$	(164,872	)	$	(67,151	)
Denominator:
Weighted average number of common shares - basic and diluted	57,093,454			55,304,083
Basic and diluted net loss attributable to common shareholders per share	$	(2.89	)	$	(1.21	)

In December 2018, the Company entered into an Open Market Sale Agreement (“2018 Sale Agreement”) with Jefferies LLC

(“Jefferies”), under which it may issue and sell common shares. In 2020, through March 2, 2020, we issued 4,127,092 common shares pursuant to the amendment to the Sale Agreement.

Government grants and refundable investment tax credits

Government grants and tax credits provided for current expenses are included in the determination of income or loss for the year, as a reduction of the expenses to which they relate.

Deferred income taxes

Income taxes are accounted for using the asset and liability method of accounting. Deferred income taxes are recognized for the future income tax consequences attributable to differences between the carrying values of assets and liabilities and their respective income tax bases and for loss carry-forwards. Deferred income tax assets and liabilities are measured using enacted income tax rates expected to apply to taxable income in the periods in which temporary differences are expected to be recovered or settled. The effect on deferred income tax assets and liabilities of a change in tax laws or rates is included in earnings in the period that includes the enactment date. When realization of deferred income tax assets does not meet the more-likely-than-not criterion for recognition, a valuation allowance is provided.

Equity-classified stock option awards

The Company grants stock options to employees, directors and consultants pursuant to share incentive plans described in note 16. Compensation expense is recorded for issued stock options using the fair value method with a corresponding increase in additional paid-in capital. Any consideration received on the exercise of stock options is credited to share capital.

The fair value of equity classified stock options is measured at the grant date and is amortized on a straight-line basis over the vesting period.

Liability-classified stock option awards

The Company accounts for liability-classified stock option awards (“liability options”) under ASC 718 - Compensation - Stock Compensation (“ASC 718”), under which awards of options that provide for an exercise price that is not denominated in: (a) the currency of a market in which a substantial portion of the Company’s equity securities trades, (b) the currency in which the employee’s pay is denominated, or (c) the Company’s functional currency, are required to be classified as liabilities. As of January 1, 2016, the Company changed its functional currency to US dollars, which resulted in certain stock option awards with exercise prices denominated in Canadian dollars having an exercise price that is not denominated in the Company’s functional currency. As such, the historic equity classification of these stock option awards changed to liability classification effective January 1, 2016. The change in classification resulted in reclassification of these awards from additional paid-in capital to a liability.

Liability options are re-measured to their fair values at each reporting date with changes in the fair value recognized in share-based compensation expense or additional paid-in capital until settlement or cancellation. Under ASC 718, when an award is reclassified from equity to liability, if at the reclassification date the original vesting conditions are expected to be satisfied, then the minimum amount of compensation cost to be recognized is based on the grant date fair value of the original award. Fair value changes below this minimum amount are recorded in additional paid-in capital.

Preferred Shares

The Company accounts for Preferred Shares under ASC 480 – Distinguishing Liabilities from Equity (“ASC 480”), which provides guidance for equity instruments with conversion features. The Company classifies Preferred Shares in its consolidated balance sheet wholly as equity, with no bifurcation of conversion feature from the host contract, given that the Preferred Shares cannot be cash-settled and the redemption features, which include a fixed conversion ratio with predetermined timing and proceeds, are within the Company’s control. The Company accrues for the 8.75% per annum compounding accrual at each reporting period end date as an increase to share capital, and an increase to deficit.

Segment information

The Company operates in a single reporting segment. Substantially all of the Company’s revenues to date were earned from customers or collaborators based in the United States. Substantially all of the Company’s premises, property and equipment are located in the United States.

Comprehensive loss

Comprehensive loss is comprised of net loss, the impact of foreign currency translation adjustments and adjustments for the change in unrealized gains and losses on investments in available-for-sale marketable securities. The Company displays comprehensive loss and its components in the consolidated statements of operations and comprehensive loss, net of tax effects if any.

Concentrations of Credit Risk

Financial instruments which potentially subject the Company to credit risk consist primarily of cash, cash equivalents and marketable securities. The Company holds these investments in highly rated financial institutions, and, by policy, limits the amounts of credit exposure to any one financial institution. These amounts at times may exceed federally insured limits. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to any significant credit risk on these funds. The Company has no off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements.

Recent accounting pronouncements

In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606. The ASU provides more comparability in the presentation of revenue for certain transactions between collaborative arrangement participants and only allows a company to present units of account in collaborative arrangements that are within the scope of the revenue recognition standard together with revenue accounted for under the revenue recognition standard. The parts of the collaborative arrangement that are not in the scope of the revenue recognition standard should be presented separately from revenue accounted for under the revenue recognition standard. The amendments in ASU No. 2018-18 are effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. The Company evaluated the impact of this pronouncement and concluded that the guidance does not have a material impact on its financial position and results of operations.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which removes, adds and modifies certain disclosure requirements for fair value measurements in Topic 820. The Company will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, and the valuation processes of Level 3 fair value measurements. However, the Company will be required to additionally disclose the changes in unrealized gains and losses included in other comprehensive income for recurring Level 3 fair value measurements, and the range and weighted average of assumptions used to develop significant unobservable inputs for Level 3 fair value measurements. The ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The amendments relating to additional disclosure requirements will be applied prospectively for only the most recent interim or annual period presented in the initial year of adoption. All other amendments will be applied retrospectively to all periods presented upon their effective date. The Company is permitted to early adopt either the entire ASU or only the provisions that eliminate or modify the requirements. The Company evaluated the impact of this pronouncement and concluded that the guidance does not have a material impact on its financial position and results of operations.

Fair Value Measurements

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Fair value measurements

air value measurements

The Company measures certain financial instruments and other items at fair value.

To determine the fair value, the Company uses the fair value hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the most observable inputs be used when available. Observable inputs are inputs market participants would use to value an asset or liability and are developed based on market data obtained from independent sources. Unobservable inputs are inputs based on assumptions about the factors market participants would use to value an asset or liability. The three levels of inputs that may be used to measure fair value are as follows:


•	Level 1 inputs are quoted market prices for identical instruments available in active markets.


•	Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability either directly or indirectly. If the asset or liability has a contractual term, the input must be observable for substantially the full term. An example includes quoted market prices for similar assets or liabilities in active markets.


•	Level 3 inputs are unobservable inputs for the asset or liability and will reflect management’s assumptions about market assumptions that would be used to price the asset or liability.

Assets and liabilities are classified based on the lowest level of input that is significant to the fair value measurements. Changes in the observability of valuation inputs may result in a reclassification of levels for certain securities within the fair value hierarchy.

The carrying values of cash and cash equivalents, investments in marketable securities, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to the immediate or short-term maturity of these financial instruments.

To determine the fair value of the contingent consideration (note 13), the Company uses a probability weighted assessment of the likelihood the milestones would be met and the estimated timing of such payments, and then the potential contingent payments were discounted to their present value using a probability adjusted discount rate that reflects the early stage nature of the development program, time to complete the program development, and overall biotech indices. The Company determined the fair value of the contingent consideration was $3.0 million as of December 31, 2019 and the decrease of $0.2 million has been recorded in other losses in the statement of operations and comprehensive loss for the year ended December 31, 2019. The assumptions used in the discounted cash flow model are level 3 inputs as defined above. The Company assessed the sensitivity of the fair value measurement to changes in these unobservable inputs, and determined that changes within a reasonable range would not result in a materially different assessment of fair value.

The following tables present information about the Company’s assets and liabilities that are measured at fair value on a recurring basis, and indicates the fair value hierarchy of the valuation techniques used to determine such fair value:



	Level 1		Level 2		Level 3		Total
As of December 31, 2019	(in thousands)
Assets
Cash and cash equivalents	$	31,799	—		—		$	31,799
Investments in marketable securities	59,035		—		—		59,035
Total	$	90,834	$	—	$	—	$	90,834
Liabilities
Liability-classified options	$	—	$	—	$	253	$	253
Contingent consideration	—		—		2,953		2,953
Total	$	—	$	—	$	3,206	$	3,206



	Level 1		Level 2		Level 3		Total
As of December 31, 2018	(in thousands)
Assets
Cash and cash equivalents	$	36,942	—		—		$	36,942
Investments in marketable securities	87,675		—		—		87,675
Total	$	124,617	$	—	$	—	$	124,617
Liabilities
Liability-classified options	$	—	$	—	$	479	$	479
Contingent consideration	—		—		3,126		3,126
Total	$	—	$	—	$	3,605	$	3,605

The following table presents the changes in fair value of the Company’s liability-classified stock option awards:



	Liability at beginning of the period		Fair value of liability-classified options exercised in the period			Increase (decrease) in fair value of liability			Liability at end of the period
	(in thousands)
Year ended December 31, 2019	$	479	$	—		$	(226	)	$	253
Year ended December 31, 2018	$	1,239	$	(93	)	$	(667	)	$	479

The following table presents the changes in fair value of the Company’s contingent consideration:



	Liability at beginning of the period		Increase (decrease) in fair value of liability			Liability at end of the period
	(in thousands)
Year ended December 31, 2019	$	3,126	$	(173	)	$	2,953
Year ended December 31, 2018	$	10,424	$	(7,298	)	$	3,126

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Equity method investment	12 Months Ended
Equity method investment	Dec. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Equity method investment	Equity method investment In April 2018, the Company entered into an agreement (the “Genevant Agreement”) with Roivant Sciences Ltd. (“Roivant”), its largest shareholder, to launch Genevant, a company focused on the discovery, development and commercialization of a broad range of RNA-based therapeutics enabled by the Company’s lipid nanoparticle (“LNP”) and ligand conjugate delivery technologies. Genevant plans to develop products in-house and pursue industry partnerships to build a diverse pipeline of therapeutics across multiple modalities, including RNAi, mRNA and gene editing. Under the terms of the Genevant Agreement, the Company contributed fixed assets with a carrying value of $0.6 million and a license for the delivery technologies. The contributed license provides Genevant with exclusive rights to the LNP and ligand conjugate delivery platforms for RNA-based applications outside of HBV and any other pre-existing licensing obligations of Arbutus. The Company retains all rights to the LNP and ligand conjugate delivery platforms for HBV, and is entitled to a tiered low single-digit royalty from Genevant on future sales of products enabled by those delivery platforms. The Company also retained the entirety of its royalty entitlement on the commercialization of Alnylam Pharmaceuticals, Inc.’s (“Alnylam”) ONPATTRO™ (Patisiran) (“ONPATTRO”). Roivant contributed $37.5 million in transaction-related seed capital to Genevant, consisting of an initial capital contribution in April 2018 of $22.5 million and a subsequent investment in June 2018 of $15.0 million at a pre-determined, stepped-up valuation, as contemplated in the initial agreement. As a result of this subsequent investment in Genevant by Roivant and other parties, the Company’s initial ownership interest in Genevant was reduced from 50% to approximately 40%. As of December 31, 2019, the Company’s ownership interest in Genevant remained approximately 40%. The Company’s contribution of licenses related to the delivery technologies and fixed assets in exchange for an equity interest in Genevant resulted in a gain for the Company of $24.9 million during the second quarter of 2018. The gain reflected the fair value of the equity in Genevant received by the Company, less the $0.6 million carrying value of the fixed assets contributed by the Company and less $1.9 million of goodwill allocated to Genevant based upon the relative fair value of Genevant to the Company as of the transaction date. The fair value of equity in Genevant received by the Company was based on a valuation performed by external valuation specialists. The basis difference between the Company’s carrying value in Genevant and the Company’s share of Genevant’s net assets is attributed primarily to indefinite-lived IPR&D (the delivery technology transferred to Genevant). The Company has significant influence over Genevant due to its ownership interest and accounts for its investment in Genevant using the equity method. The Company’s proportionate share of Genevant’s financial results are recorded on a one-quarter lag basis. The Company recorded non-cash equity losses of $22.5 million for the year ended December 31, 2019 and non-cash equity gains of $19.6 million for the year ended December 31, 2018. Equity losses for 2019 included $14.9 million of losses for the Company’s proportionate share of Genevant’s net losses and a $7.6 million impairment charge to reduce the carrying value of the Company’s investment in Genevant to zero. The impairment was due to uncertainty surrounding the recovery of the Company’s remaining carrying value in Genevant. Equity gains for 2018 included the $24.9 million gain on the Company’s contribution of delivery technology licenses upon formation of Genevant, partially offset by

Investments in marketable securities

12 Months Ended

Dec. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Investments in marketable securities

Investments in marketable securities consisted of the following:



	Amortized Cost		Gross Unrealized Gain⁽¹⁾		Gross Unrealized Loss⁽¹⁾			Fair Value
As of December 31, 2019	(in thousands)
Cash equivalents
Money market fund	$	4,106	$	—	$	—		$	4,106
US government agency bonds	1,511		—		—			1,511
US treasury bills	1,499		—		—			1,499
Total	$	7,116	$	—	$	—		$	7,116
Investments in marketable securities
US government agency bonds	$	19,863	$	2	$	(1	)	$	19,864
US treasury bills	15,926		2		$	(1	)	15,927
US government bonds	23,246		—		(2		)	23,244
Total	$	59,035	$	4	$	(4	)	$	59,035

⁽¹⁾Gross unrealized gain (loss) is pre-tax.



	Amortized Cost		Gross Unrealized Gain⁽¹⁾		Gross Unrealized Loss⁽¹⁾		Fair Value
As of December 31, 2018	(in thousands)
Cash equivalents
Individual savings account	$	20,420	$	—	$	—	$	20,420
Total	$	20,420	$	—	$	—	$	20,420
Investments in marketable securities
Canadian guaranteed investment certificates	$	71,483	$	—	$	—	$	71,483
USD term deposit	16,192		—		$	—	$	16,192
Total	$	87,675	$	—	$	—	$	87,675

⁽¹⁾Gross unrealized gain (loss) is pre-tax.

The contractual term to maturity of short-term marketable securities held by the Company as of December 31, 2019 is less than one year. There were no long-term marketable securities held by the Company as of December 31, 2019.

There were no realized gains or losses for the year ended December 31, 2019 or 2018.

Leases

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Leases

The Company has two operating leases for office and laboratory space. The Company’s corporate headquarters is located at 701 Veterans Circle, Warminster, Pennsylvania. The lease expires on April 30, 2027, and the Company has the option of extending the lease for two further five-year terms. The Company also leases office space located at 626 Jacksonville Rd, Warminster, Pennsylvania under a lease that expires on December 31, 2021, and the Company has an option to extend the lease term to April 30, 2027. In connection with the Company’s site consolidation in 2018, the Company ceased using its office and laboratory space located in Burnaby, British Columbia, Canada on June 30, 2018. The Company subleased a portion of the Burnaby facility to various tenants, including Genevant, until the lease expired on July 31, 2019. The Company recognized the remaining lease payments for the Burnaby facility, less sublease income under contract, in site consolidation expenses in 2018. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants.

The Company adopted ASU No. 2016-02, Leases (Topic 842) on January 1, 2019 using the modified retrospective basis applied at the effective date of the new standard and elected to utilize a package of practical expedients. Leases with an initial term of 12 months or less are not recorded on the balance sheet. The Company determines if an arrangement is a lease at inception. Right-of-use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease right-of-use assets and lease liabilities are recognized based on the present value of lease payments over the lease term. The leases do not provide an implicit rate so, in determining the present value of lease payments, the Company utilized its incremental borrowing rate for the applicable lease, which was 9.0% for the 701 Veterans Circle lease, 7.6% for the 626 Jacksonville Rd. lease and 5.0% for the Burnaby lease. The Company recognizes lease expense on a straight-line basis over the remaining lease term.

During the year ended December 31, 2019, the Company incurred total operating lease expenses of $1.2 million, which included lease expenses associated with fixed lease payments of $0.9 million, and variable payments associated with common area maintenance and similar expenses of $0.3 million. For the twelve months ended December 31, 2018, the straight-line fixed expense for leases was $1.4 million. Sublease income for the twelve months ended December 31, 2019 was $0.2 million, versus $0.2 million for the twelve months ended December 31, 2018.

Weighted average remaining lease term and discount rate were as follows:



	As of December 31, 2019
Weighted-average remaining lease term (years)	7.0
Weighted average discount rate	8.9%

The Company did not include options to extend its lease terms as part of its ROU asset and lease liabilities.

Supplemental cash flow information related to the Company’s operating leases was as follows:



	2019		2018
	(in thousands)
Cash paid for amounts included in the measurement of lease liabilities	$	1,116	$	—

Future minimum lease payments under operating leases that have remaining terms as of December 31, 2019 are as follows:



	As of December 31, 2019
	(in thousands)
2020	$	657
2021	677
2022	581
2023	598
2024	616
Thereafter	1,423
Total Lease Payments	$	4,552
Less: interest	(1,193		)
Present value of lease payments	$	3,359

Property and Equipment

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Property and equipment

The Company’s property and equipment balances as of the years ended December 31, 2019 and 2018 are as follows:



	Cost		Accumulated depreciation			Net book value
December 31, 2019	(in thousands)
Lab equipment	$	5,511	$	(3,316	)	$	2,195
Leasehold improvements	8,521		(2,152		)	6,369
Computer hardware and software	286		(174		)	112
	$	14,318	$	(5,642	)	$	8,676



	Cost		Accumulated depreciation			Net book value
December 31, 2018	(in thousands)
Lab equipment	$	5,420	$	(2,455	)	$	2,965
Leasehold improvements	9,308		(2,401		)	6,907
Computer hardware and software	2,313		(2,040		)	273
	$	17,041	$	(6,896	)	$	10,145

During 2019, the Company closed its Burnaby facility and the lease expired according to its terms on July 31, 2019. In connection with the facility closure, the Company disposed of $3.4 million of equipment, furniture and leasehold improvements. Most of the disposed assets were fully depreciated. The aggregate net book value of the disposed assets was less than $0.1 million.

Intangible Assets and Goodwill	12 Months Ended
Intangible Assets and Goodwill	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets and goodwill	Intangible assets and goodwill All IPR&D intangible asset balance related to the Company’s cccDNA program. During 2019, the Company recorded a $43.8 million non-cash impairment expense to reduce the carrying value of its IPR&D intangible assets to zero. The Company also recognized a corresponding income tax benefit of $12.7 million related to the decrease in its deferred tax liability related to the IPR&D intangible assets. The impairment was due to a decision to delay indefinitely the further development of the Company’s cccDNA program while the Company focuses on its other development programs. In 2018, the Company recorded a $14.8 million intangible assets impairment charge, and a corresponding income tax benefit of $4.3 million related to the decrease in deferred tax liability, for the indefinite delay of further development of its AB-423 program. The Company’s goodwill balance represented the excess of purchase price over the value assigned to the net tangible and identifiable intangible assets in connection with the business combination that formed Arbutus. During 2019, the Company assessed its changes in circumstances to determine if it was more likely than not that the fair value of its single reporting unit was below its carrying amount. Due to a sustained decrease in the Company’s share price in recent months, the Company’s market capitalization was reduced below the book value of its net assets and the Company concluded that the fair value of its single reporting unit was below its carrying amount in excess of the carrying value of goodwill. As a result, the Company recorded a $22.5 million non-cash impairment expense to reduce the carrying value of its goodwill asset to zero.

Accounts Payable and Accrued Liabilities

12 Months Ended

Dec. 31, 2019

Payables and Accruals [Abstract]

Accounts payable and accrued liabilities

Accounts payable and accrued liabilities are comprised of the following:



	December 31, 2019		December 31, 2018
	(in thousands)
Trade accounts payable	$	2,398	$	3,192
Payroll accruals	2,314		2,341
Research and development accruals	1,433		2,716
Professional fee accruals	809		871
Other accrued liabilities	144		309
Total	$	7,098	$	9,429

Site Consolidation

12 Months Ended

Dec. 31, 2019

Restructuring and Related Activities [Abstract]

Site consolidation

In 2018, the Company substantially completed a site consolidation and organizational restructuring to align its HBV business in Warminster, PA, including a reduction of its global workforce and closure of its Burnaby facility. The Company estimates that the total expenses to complete the site consolidation will be approximately $5.0 million, of which $4.9 million has been incurred as of December 31, 2019. Included in the site consolidation plan was the payment of one-time employee termination benefits, employee relocation costs, and site closure costs. The Company ceased the use of its Burnaby facility as of June 2018 and the Company entered into subleases with various tenants, including Genevant, for a portion of the Burnaby facility. The Company recorded the remaining committed cost, less sublease income under contract, in site consolidation expenses in 2018. The lease of the Burnaby facility expired on July 31, 2019.

The Company accounts for site consolidation expense in accordance with ASC 420, Exit or Disposal Cost Obligations (“ASC 420”). ASC 420 specifies that a liability for a cost associated with an exit or disposal activity be recognized when the liability is incurred, except for a liability where employees are required to render service until they are terminated in order to receive termination benefits and will be retained to render service beyond the minimum retention period. A liability for such one-time termination benefits shall be measured initially at the communication date based on the fair value of the liability as of the termination date and recognized ratably over the future service period.

The following table shows the changes to the site consolidation accrual for the twelve months ended December 31, 2019:



	For the Twelve Months Ended December 31, 2019
	(in thousands)
Accrual Balance December 31, 2018	$	1,331

Employee severance and relocation expense	510
Lease and facility expense	(347		)
Total site consolidation expense	$	163

Amounts paid and adjustments	(1,357		)
Accrual Balance December 31, 2019	$	137

Loan Payable	12 Months Ended
Loan Payable	Dec. 31, 2019
Debt Disclosure [Abstract]
Loan payable	Loan payable During 2018, the Company had a bank loan of $12.0 million in the form of a promissory note for the purpose of financing its operations and expanding its laboratory facilities in the United States. The loan accrued interest daily at a rate of one-month London Interbank Offered Rate (LIBOR) plus 1.25% per annum. The maturity date of the loan was December 27, 2019. The loan was secured by the Company’s cash of $12.6 million and was restricted from use until the loan was settled in full. The Company invested the restricted cash in a two-year fixed certificate of deposit with a bank and was presented as restricted investment in the Company’s balance sheet for the period ended December 31, 2017. In March 2018, the Company repaid the loan and accrued interest in full, resulting in the release of $12.6 million from restricted cash to investments in marketable securities on the Company’s condensed consolidated balance sheet.

Sale of future royalties (Notes)

12 Months Ended

Dec. 31, 2019

Other Liabilities Disclosure [Abstract]

Sale of future royalties

On July 2, 2019, the Company entered into a Purchase and Sale Agreement (the “Agreement”) with the Ontario Municipal Employees Retirement System (“OMERS”), pursuant to which the Company sold to OMERS part of its royalty interest on future global net sales of ONPATTRO, an RNA interference therapeutic currently being sold by Alnylam.

ONPATTRO utilizes Arbutus’s LNP technology, which was licensed to Alnylam pursuant to the Cross-License Agreement, dated November 12, 2012, by and between the Company and Alnylam (the “LNP License Agreement”). Under the terms of the LNP License Agreement, the Company is entitled to tiered royalty payments on global net sales of ONPATTRO ranging from 1.00% to 2.33% after offsets, with the highest tier applicable to annual net sales above $500 million. This royalty interest was sold to OMERS, effective as of January 1, 2019, for $20 million in gross proceeds before advisory fees. OMERS will retain this entitlement until it has received $30 million in royalties, at which point 100% of such royalty interest on future global net sales of ONPATTRO will revert to the Company. OMERS has assumed the risk of collecting up to $30 million of future royalty payments from Alnylam and Arbutus is not obligated to reimburse OMERS if they fail to collect any such future royalties.

The $30 million in royalties to be paid to OMERS is accounted for as a liability, with the difference between the liability and the gross proceeds received accounted for as a discount. The discount, as well as $1.5 million of transaction costs, will be amortized as interest expense based on the projected balance of the liability as of the beginning of each period. Management estimated an effective annual interest rate of approximately 22%. Over the course of the Agreement, the actual interest rate will be affected by the amount and timing of royalty revenue recognized and changes in the timing of forecasted royalty revenue. On a quarterly basis, the Company will reassess the expected timing of the royalty revenue, recalculate the amortization and effective interest rate and adjust the accounting prospectively as needed.

The Company recognizes non-cash royalty revenue related to the sales of ONPATTRO during the term of the Agreement. As royalties are remitted to OMERS from Alnylam, the balance of the recognized liability is effectively repaid over the life of the Agreement. There are a number of factors that could materially affect the amount and timing of royalty payments from Alnylam, none of which are within the Company’s control.

During the year ended December 31, 2019, the Company recognized non-cash royalty revenue of $1.7 million and $2.1 million of related non-cash interest expense.

The table below shows the activity related to the net liability from inception of the Agreement through December 31, 2019:



	Twelve Months Ended December 31, 2019
	(in thousands)
Net liability related to sale of future royalties - beginning balance	$	—
Initial recognition of liability	30,000
Debt discount and issuance costs	(11,451		)
Non-cash interest expense	2,099
Net debt discount and issuance costs	(9,352		)
Non-cash royalty revenue	(1,656		)
Net liability related to sale of future royalties - ending balance	$	18,992

In addition to the royalty from the Alnylam LNP License Agreement, the Company is also receiving a second, lower royalty interest on global net sales of ONPATTRO originating from a settlement agreement and subsequent license agreement with Acuitas Therapeutics, Inc. (“Acuitas”). The royalty from Acuitas has been retained by the Company and was not part of the royalty sale to OMERS.

Contingencies and Commitments	12 Months Ended
Contingencies and Commitments	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Contingencies and commitments	Contingencies and commitments Product development partnership with the Canadian Government The Company entered into a Technology Partnerships Canada (“TPC”) agreement with the Canadian Federal Government on November 12, 1999. Under this agreement, TPC agreed to fund 27% of the costs incurred by the Company, prior to March 31, 2004, in the development of certain oligonucleotide product candidates up to a maximum contribution from TPC of $7.2 million (C$9.3 million). The Company received a cumulative contribution of $2.7 million (C$3.7 million). In return for the funding provided by TPC, the Company agreed to pay royalties on the share of future licensing and product revenue, if any, that is received by the Company on certain non-RNAi oligonucleotide product candidates covered by the funding under the agreement. These royalties are payable until a certain cumulative payment amount is achieved or until a pre-specified date. In addition, until a cumulative amount equal to the funding actually received under the agreement has been paid to TPC, the Company agreed to pay 2.5% royalties on any royalties the Company receives for Marqibo. For the years ended December 31, 2019 and 2018, the Company earned royalties on Marqibo sales in the amounts of $0.3 million and $0.2 million, respectively. The resulting royalties payable by the Company to TPC were not material in either period. The cumulative amount paid or accrued up to December 31, 2019 was less than $0.1 million, resulting in the contingent amount due to TPC being $2.7 million (C$3.7 million). Arbitration with the University of British Columbia Certain early work on lipid nanoparticle delivery systems and related inventions was undertaken at the University of British Columbia (“UBC”), as well as by us that was subsequently assigned to UBC. These inventions are licensed to the Company by UBC under a license agreement, initially entered into in 1998 and as amended in 2001, 2006 and 2007. The Company has granted sublicenses under the UBC license to certain third parties, including Alnylam. In November 2014, UBC filed a demand for arbitration against the Company and in January 2015, filed a Statement of Claim, which alleged entitlement to $3.5 million in allegedly unpaid royalties based on publicly available information, and an unspecified amount based on non-public information. UBC also sought interest and costs, including legal fees. The Company filed its Statement of Defense to UBC’s Statement of Claims, as well as a Counterclaim involving a patent application that the Company alleged UBC wrongly licensed to a third party. The proceedings were divided into three phases, with the first hearing taking place in June 2017. In the first phase, the arbitrator determined which agreements are sublicense agreements within UBC’s claim. Also in the first phase, UBC updated its alleged entitlement from $3.5 million originally claimed to seek $10.9 million in alleged unpaid royalties, plus interest arising from payments as early as 2008. The arbitrator also held in the first phase of the arbitration that the patent application that is the subject of the Counterclaim was not required to be licensed to Arbutus. The second phase of arbitration took place in the second quarter of 2019. In August 2019, the arbitrator issued his decision for the second phase of the arbitration, awarding UBC $5.9 million, which includes interest of approximately$2.6 million. The Company paid the $5.9 million award to UBC in September 2019. The arbitrator also held that the third phase of the arbitration, which would address patent validity, should the Company choose to pursue a third phase, would not provide a defense to the award. An award for costs and attorneys’ fees is still to be determined. The Company recorded a charge of $6.3 million in 2019 consisting $5.9 million for the award (including interest) and $0.4 million for an estimate of a potential award for costs and attorneys’ fees. License Agreements between Enantigen In October 2014, Arbutus Inc. acquired all of the outstanding shares of Enantigen Therapeutics, Inc. (“Enantigen”) pursuant to a stock purchase agreement. Through this transaction, Arbutus Inc. acquired a HBV surface antigen secretion inhibitor program and a capsid assembly inhibitor program. Under the stock purchase agreement, Arbutus Inc. agreed to pay up to a total of $21.0 million to Enantigen’s selling stockholders upon the achievement of specified development and regulatory milestones for (a) the first two products that contain either a capsid compound or an HBV surface antigen compound that is covered by a patent acquired under this agreement, or (b) a capsid compound from an agreed-upon list of compounds. The development milestones are tied to programs which are no longer under development by us, and therefore the contingency related to these milestones has been reduced to zero. An additional $102.5 million may also be paid to Enantigen’s selling stockholders related to the achievement of certain sales performance milestones in connection with the sale of the first commercialized product by Arbutus Inc. for the treatment of HBV, regardless of whether such product is based upon assets acquired under this agreement, and a low single-digit royalty on net sales of such first commercialized HBV product, up to a maximum royalty payment of $1.0 million that, if paid, would be offset against Arbutus Inc.’s milestone payment obligations. The contingent consideration is a financial liability and is measured at its fair value at each reporting period, with any changes in fair value from the previous reporting period recorded in the statement of operations and comprehensive loss (note 3). The fair value of the contingent consideration was $3.0 million as of December 31, 2019.

Collaborations, Contracts and Licensing Agreements	12 Months Ended
Collaborations, Contracts and Licensing Agreements	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Collaborations, contracts and licensing agreements	Collaborations, contracts and licensing agreements Alnylam Pharmaceuticals, Inc. In 2012, the Company entered into a license agreement with Alnylam that entitles Alnylam to develop and commercialize products with the Company’s LNP technology. During the third quarter of 2018, Alnylam’s ONPATTRO, which utilizes the Company’s LNP technology, was approved by the U.S. Food and Drug Administration (“FDA”) and the European Medicines Agency. The Company is entitled to tiered low to mid single-digit royalty payments on global net sales of ONPATTRO and received its first royalty payment in the fourth quarter of 2018. In July 2019, the Company sold a portion of its royalty entitlement for Alnylam’s ONPATTRO to OMERS. See note 12 for further details. The Company recognized $1.7 million of non-cash revenue and $0.2 million of cash revenue based on global net sales of Alnylam’s ONPATTRO for the year ended December 31, 2019 and 2018, respectively. Acuitas Therapeutics, Inc. The Company has rights to a second royalty interest on global net sales of ONPATTRO originating from a settlement agreement and subsequent license agreement with Acuitas. This royalty entitlement from Acuitas has been retained by us and was not part of the royalty entitlement sale to OMERS. The Company recognized $1.9 million and $1.0 million of revenue from Acuitas based on global net sales of Alnylam’s ONPATTRO for the years ended December 31, 2019 and 2018, respectively. Gritstone Oncology, Inc. On October 16, 2017, the Company entered into a license agreement with Gritstone Oncology, Inc. (“Gritstone”) that entitles Gritstone to research, develop, manufacture and commercialize products with the Company’s LNP technology. The Company received an upfront payment in November 2017, and is eligible to receive future potential payments including development and commercial milestone payments, royalty payments on future product sales and payments for research services provided. As a result of the Company’s agreement with Genevant (see note 5 for details), from April 11, 2018 going forward, Genevant is entitled to 50% of the revenues earned by the Company from Gritstone. The Company is the agent in this arrangement and records revenue on a net basis. In 2018, Gritstone paid a development milestone payment of $2.5 million pursuant to the license agreement and the Company recorded related revenue, net of the portion paid to Genevant, of $1.3 million. Milestone payments that are not within the control of the Company or the licensee, such as those that require regulatory approvals, are not considered probable of being achieved until those approvals are received. The Company recognized $1.8 million and $4.3 million of revenue from Gritstone for the years ended December 31, 2019 and 2018, respectively. Acrotech Biopharma LLC and Spectrum Pharmaceuticals, Inc. In May 2006, the Company signed a number of agreements with Talon Therapeutics, Inc. (“Talon”, formerly Hana Biosciences, Inc.) including the grant of worldwide licenses (the “Talon License Agreement”) for three of the Company’s chemotherapy products, Marqibo®, Alocrest ™ (Optisomal Vinorelbine) and Brakiva ™ (Optisomal Topotecan). In 2012, Talon had received approval for Marqibo from the FDA for the treatment of adult patients with Philadelphia chromosome negative acute lymphoblastic leukemia in second or greater relapse or whose disease has progressed following two or more anti-leukemia therapies. Marqibo is a liposomal formulation of the chemotherapy drug, vincristine. In 2012, the Company received a milestone of $1.0 million based on the FDA’s approval of Marqibo and receives royalty payments based on Marqibo’s commercial sales. There are no further milestones related to Marqibo but the Company is eligible to receive total milestone payments of up to $18.0 million on Alocrest and Brakiva. Talon was acquired by Spectrum Pharmaceuticals, Inc. in July 2013, who subsequently sold the license of Marqibo to Acrotech Biopharma LLC in January 2019. The acquisitions and license sale did not affect the terms of the license between Talon and the Company. The Company recognized $0.6 million and $0.2 million of revenue related to sales of Marqibo for the years ended December 31, 2019 and 2018, respectively.

Shareholders' Equity	12 Months Ended
Shareholders' Equity	Dec. 31, 2019
Equity [Abstract]
Shareholders' equity	Shareholders’ equity Authorized share capital The Company’s authorized share capital consists of an unlimited number of common shares and 1,164,000 preferred shares without par value. Open Market Sale Agreement In December 2018, the Company entered into the 2018 Sale Agreement with Jefferies, under which it may issue and sell common shares, from time to time, for an aggregate sales price of up to $50.0 million. For the twelve months ended December 31, 2019, the Company issued 9,138,232 common shares pursuant to the Sale Agreement, resulting in gross proceeds of approximately $19.5 million. There were no shares issued during the twelve months ended December 31, 2018 under the Sale Agreement. In December 2019, the Company entered into an amendment to the Sale Agreement with Jefferies in connection with filing a new shelf registration statement on Form S-3 (File No. 333-235674), filed with the SEC on December 23, 2019 (the “New Shelf Registration Statement”). The Amendment revised the Sale Agreement to reflect that we may sell our common shares, without par value, from time to time for an aggregate sales price of up to $50.0 million, under the New Shelf Registration Statement. In 2020, through March 2, 2020, we issued 4,127,092 common shares pursuant to the amendment to the Sale Agreement, resulting in net proceeds of approximately $12.3 million. Series A Preferred Shares On October 2, 2017, the Company announced that it entered into a subscription agreement with Roivant for the sale of Preferred Shares to Roivant for gross proceeds of $116.4 million. The Preferred Shares are non-voting and are convertible into common shares at a conversion price of $7.13 per share (which represents a 15% premium to the closing price of $6.20 per share). The purchase price for the Preferred Shares plus an amount equal to 8.75% per annum, compounded annually, will be subject to mandatory conversion into common shares on October 18, 2021 (subject to limited exceptions in the event of certain fundamental corporate transactions relating to Arbutus’ capital structure or assets, which would permit earlier conversion at Roivant’s option). Assuming conversion of the Preferred Shares into common shares, based on the number of common shares outstanding on December 31, 2019 Roivant would hold 42% of the Company’s common shares. Roivant has agreed to a four year lock-up period for this investment and its existing holdings in Arbutus. Roivant has also agreed to a four year standstill whereby Roivant will not acquire greater than 49.99% of the Company’s common shares or securities convertible into common shares. The initial investment of $50.0 million closed on October 16, 2017, and the remaining amount of $66.4 million closed on January 12, 2018 following regulatory and shareholder approvals. The Company records the Preferred Shares wholly as equity under ASC 480, with no bifurcation of conversion feature from the host contract, given that the Preferred Shares cannot be cash settled and the redemption features are within the Company’s control, which include a fixed conversion ratio with predetermined timing and proceeds. The Company accrues for the 8.75% per annum compounding coupon at each reporting period end date as an increase to share capital, and an increase to deficit (see statement of stockholder’s equity).

Stock-based Compensation

12 Months Ended

Dec. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-based compensation

Awards outstanding and available for issuance

During the year ended December 31, 2019, the Company had stock options outstanding under the following plans: the 2016 Omnibus Share and Incentive Plan (the “2016 Plan”), the 2011 Omnibus Share Compensation Plan (the “2011 Plan”), the 2013 designated plans (the “Designated Plans”), the 2019 inducement grant and the OnCore Option Plan.

As of December 31, 2019, the aggregate number of shares authorized for awards under all Plans was 12,790,202. As of December 31, 2019, the Company had 8,576,584 options outstanding and a further 2,424,703 awards available for issuance.

The Company issues new shares of common stock to settle options exercised.

Under the 2016 and 2011 Plans, the Company’s board of directors may grant options, and other types of Awards, to employees, directors and consultants of the Company. The exercise price of the options is determined by the Company’s Board of Directors but will be at least equal to the closing market price of the common shares on the date of grant or the prior day and the term may not exceed 10 years. Options granted generally vest over three or four years for employees and for directors’ initial grants, and immediately for directors’ annual grants.

Additionally, the Company granted a total of 200,000 options in 2013 to two executive officers in conjunction with their new appointments as executive officers. These options were granted in accordance with the policies of the Toronto Stock Exchange and pursuant to newly designated share compensation plans (the “Designated Plans”). The Designated Plans are governed by substantially the same terms as the 2011 Plan. No new options can be granted under the Designated Plans. There were 150,000 options outstanding for one of the Company’s former executive officers as of December 31, 2018, all of which expired unexercised in February 2019.

In June 2019, the Company provided an inducement grant of 1,112,000 options to its newly hired Chief Executive Officer. These options were awarded in a separate plan as non-qualified awards and are governed by the substantially the same terms as the 2016 Plan.

Hereafter, information on options governed by the 2016 Plan, the 2011 Plan, the 2007 Plan, the Designated Plans and inducement grant (the “Arbutus Plans”) is presented on a consolidated basis as the terms of the plans are similar. Information on the OnCore Option Plan is presented separately.

Stock options under the Arbutus Plans

Equity-classified stock options under the Arbutus Plans

The following table summarizes activity related to the Company’s equity-classified stock options for the year ended December 31, 2019:



	Stock Options Outstanding				Vested Stock Options		Non-Vested Stock Options
	Number		Weighted-Average Exercise Price		Number		Number		Weighted-Average Grant-Date Fair Value
Balance as of December 31, 2018	6,331,088		$	6.05	2,620,542		3,710,546		$	3.39
Options granted	3,018,000		$	3.41	—		3,018,000		$	2.43
Options exercised	(83,000	)	$	3.25	(83,000	)	—		$	—
Options forfeit, canceled or expired	(1,016,995	)	$	6.98	(477,848	)	(539,147	)	$	3.24
Options vested	—		$	—	2,234,955		(2,234,955	)	$	3.10
Balance as of December 31, 2019	8,249,093		$	5.00	4,294,649		3,954,444		$	2.86

The intrinsic value of options exercised under the Arbutus plans during 2019 and 2018 are less than $0.1 million and $1.1 million, respectively.

The following table summarizes additional information related to the Company’s equity-classified stock options as of December 31, 2019:



	As of December 31, 2019
Options outstanding and expected to vest
Number of stock options outstanding	8,249,093
Weighted-average exercise price	$	5
Intrinsic value (in $000s)	$	1,001
Weighted-average term remaining	6.9 years
Vested stock options
Number of vested stock options	4,294,649
Weighted-average exercise price	$	5.85
Intrinsic value (in $000s)	$	189
Weighted-average term remaining	5.0 years

On March 3, 2015, the Company voluntarily de-listed from the Toronto Stock Exchange. All stock options granted after March 3, 2015 were denominated in US dollars based on the Company’s stock price on the Nasdaq Global Select Market. The methodology and assumptions used to estimate the fair value of stock options at date of grant under the Black-Scholes option-pricing model remain unchanged. Assumptions on the dividend yield are based on the fact that the Company has never paid cash dividends and has no present intention to pay cash dividends. Assumptions about the Company’s expected stock-price volatility are based on the historical volatility of the Company’s publicly traded stock. The risk-free interest rate used for each grant is equal to the zero coupon rate for instruments with a similar expected life. Expected life assumptions are based on the Company’s historical data.

The assumptions used in the Black-Scholes option-pricing for grants made during the years ended December 31, 2019 and 2018 are as follows:



	December 31, 2019		December 31, 2018
Expected average option term	7.3 years		6.7 years
Expected volatility	75.9	%	75.2	%
Expected dividends	—	%	—	%
Risk-free interest rate	2.27	%	2.81	%

Liability-classified stock options under the Arbutus Plans

Due to the change in the Company’s functional currency as of January 1, 2016, certain stock option awards with exercise prices denominated in Canadian dollars changed from equity classification to liability classification (see note 2).

The following table summarizes activity related to the Company’s liability-classified stock options for the year ended December 31, 2019:



	Stock Options Vested and Outstanding
	Number		Weighted-Average Exercise Price
Balance as of December 31, 2018	377,500		$	5.81
Options exercised	—		$	—
Options forfeit, canceled or expired	(150,000	)	$	7.01
Balance as of December 31, 2019	227,500		$	5.49

There were no exercises of liability-classified stock options during 2019. The intrinsic value of liability-classified options exercised during 2018 was $0.1 million.

The following table summarizes additional information related to the Company’s liability-classified stock options as of December 31, 2019:



	As of December 31, 2019
Options outstanding and expected to vest
Intrinsic value (in $000s)	$	96
Weighted-average term remaining	1.6 years

Liability options are re-measured to their fair values at each reporting date, using the Black-Scholes valuation model. The methodology and assumptions prevailing at the re-measurement date used to estimate the fair values of liability options remain unchanged from the date of grant of equity classified stock option awards. Assumptions about the Company’s expected stock-price volatility are based on the historical volatility of the Company’s publicly traded stock. The risk-free interest rate used for each grant is equal to the zero coupon rate for instruments with a similar expected life. Expected life assumptions are based on the Company’s historical data.

The weighted average Black-Scholes option-pricing assumptions and the resultant fair values as of December 31, 2019 and December 31, 2018, are presented in the following table:



	December 31, 2019			December 31, 2018
Stock price	$	2.78		$	3.83
Expected average option term	1.6 years			2.2 years
Expected volatility	113.1		%	75.2		%
Expected dividends	—		%	—		%
Risk-free interest rate	1.59		%	2.48		%
Weighted-average fair value per share	$	1.11		$	1.27
Total fair value of vested liability-classified options (in $000s)	$	253		$	479

OnCore Option Plan

As of the acquisition date in March 2015, the Company reserved 184,332 shares for the future exercise of OnCore stock options. The total fair value of OnCore stock options at the date of acquisition was $3.3 million, using the Black-Scholes pricing model with an assumed risk-free interest rate of 0.97%, volatility of 78%, a zero dividend yield and an expected life of 8.0 years, which are consistent with the assumption inputs used by the Company to determine the fair value of its options. Of the total fair value, $1.1 million was attributed as pre-combination service and included as part of the total acquisition consideration. The post-combination attribution of $2.2 million was recognized as compensation expense over the vesting period of the stock options through December 2018.

Following the merger, the Company is not permitted to grant any further options under the OnCore Option Plan.

The following table summarizes activity related to the OnCore stock options for the year ended December 31, 2019:



	Stock Options Vested and Outstanding
	Number of OnCore Options		Number of Equivalent Company Common Shares		Weighted-Average Exercise Price
Balance as of December 31, 2018	139,290		140,273		$	0.56
Options exercised	(40,000	)	(40,282	)	$	0.58
Options forfeit, canceled or expired	—		—		$	—
Balance as of December 31, 2019	99,290		99,991		$	0.56

The intrinsic value of options exercised under the OnCore plan during 2019 and 2018 was $0.1 million and $0.3 million, respectively.

The following table summarizes additional information related to the OnCore stock options as of December 31, 2019:



	As of December 31, 2019
Vested stock options
Intrinsic value (in $000s)	$	222,248
Weighted-average term remaining	4.9 years

Stock-based compensation expense

Total stock-based compensation expense was comprised of: (1) vesting of options awarded to employees under the Arbutus and OnCore Plans calculated in accordance with the fair value method as described above; and (2) fair value adjustments for the Company’s liability-classified stock options.

The Company recognizes forfeitures as they occur, and the effects of forfeitures are reflected in stock-based compensation expense.

Stock-based compensation has been recorded in the consolidated statement of operations and comprehensive income (loss) as follows:



	Year Ended December 31
	2019		2018
	(in thousands)
Research and development	$	2,971	$	2,670
General and administrative	3,828		3,337
Total	$	6,799	$	6,007

During the year ended December 31, 2019, the Company recognized $1.1 million of non-cash stock-based compensation expense for the accelerated vesting stock options, related to the departure of the Company’s former President and Chief Executive Officer in June of 2019.

At December 31, 2019, there remains $6.8 million of unearned compensation expense related to unvested equity employee stock options to be recognized as expense over a weighted-average period of approximately 2.1 years.

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income taxes

Income tax (benefit) expense varies from the amounts that would be computed by applying the combined Canadian federal and provincial income tax rate of 27% (2018 - 27%) to the loss before income taxes as shown in the following tables:



	Year ended December 31,
	2019			2018
	(in thousands)
Computed taxes (benefits) at Canadian federal and provincial tax rates	$	(44,922	)	$	(16,563	)
Difference between statutory rate and foreign rate	8,356			—
Adjustments to prior year	(525		)	—
Permanent and other differences	3,458			(2,328		)
Change in valuation allowance - other	19,078			13,062
Difference due to income taxed at foreign rates	(3,343		)	(138		)
Stock-based compensation	523			1,685
Impairment of goodwill	4,719			—
Deferred income tax benefit	$	(12,656	)	$	(4,282	)

As of December 31, 2019, the Company has investment tax credits available to reduce Canadian federal income taxes of $10.0 million, versus $8.8 million as of December 31, 2018, which expire between 2027 and 2037, and provincial income taxes of $4.5 million, versus $4.0 million as of December 31, 2018, which expire between 2024 and 2027. In addition, the Company has research and development credits of $3.9 million as of December 31, 2019, versus the $4.3 million it had as of December 31, 2018, which expire between 2031 and 2038 and which can be used to reduce future taxable income in the United States.

As of December 31, 2019, the Company had scientific research and experimental development expenditures of $60.6 million available for indefinite carry-forward, versus the $61.5 million it had as of December 31, 2018. The Company also had net operating losses of $164.9 million as of December 31, 2019 and $182.3 million as of December 31, 2018, which are due to expire between 2031 and 2038 and which can be used to offset future taxable income in Canada.

As of December 31, 2019, the Company had $11.7 million of net operating losses due to expire in 2035 and $62.0 million of net operating losses subject to an indefinite carryforward period which can be used to offset future taxable income in the United States, versus the $11.0 million the Company had as of December 31, 2018. Future use of a portion of the United States loss carry-forwards is subject to limitations under the Internal Revenue Code Section 382.

As a result of ownership changes occurring on October 1, 2014 and March 4, 2015, the Company’s ability to use these losses may be limited. Losses incurred to date may be further limited if a subsequent change in control occurs.

The Company generated $27.1 million and $139.3 million in pre-tax domestic and foreign losses, respectively, for the year ended December 31, 2019.

Significant components of the Company’s deferred tax assets and liabilities are shown below:



	As of December 31,
	2019			2018
	(in thousands)
Deferred tax assets (liabilities):
Non-capital loss carryforwards	$	59,956		$	51,575
Research and development deductions	16,349			15,803
Book amortization in excess of tax	(914		)	(608		)
Share issue costs	202			307
Revenue recognized for tax purposes in excess of revenue recognized for accounting purposes	5,128			—
Tax value in excess of accounting value in lease inducements	705			147
Federal investment tax credits	7,325			9,686
Provincial investment tax credits	4,535			3,955
In-process research and development	—			(12,664		)
Upfront license fees	236			283
Equity accounted for investment	3,038			37
Other	6,202			2,503
Total deferred tax assets (liabilities)	102,762			71,024
Valuation allowance	(102,762		)	(83,685		)
Net deferred tax assets (liabilities)	$	—		$	(12,661	)

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2019
Related Party Transactions [Abstract]
Related party transactions	Related Party Transactions During 2018, the Company purchased certain research and development services from Roivant, which were billed at agreed hourly rates and reflective of market rates for such services. The total cost of these services was $0.6 million during 2018 and was recorded in the income statement in research and development. There were no such purchases in 2019. During 2018, the Company also purchased certain research and development services from its equity method investee, Genevant. These services were billed at agreed hourly rates and reflective of market rates for such services. The total cost of these services was $0.4 million during 2018 and were included in the income statement in research and development. There were no such purchases during 2019. Conversely, Genevant purchased certain administrative and transitional services from the Company totaling $0.1 million and $0.2 million during 2019 and 2018, respectively, and these costs were netted in research and development in the income statement. In addition, Genevant had a sublease for 17,900 square feet in the Company’s Burnaby facility. Sublease income, including management fee reimbursements, from Genevant was $0.2 million and $0.2 million, in 2019 and 2018, respectively, which was netted against site consolidation costs in the income statement (note 10).

Interim Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Interim financial data (unaudited)

Summarized unaudited quarterly financial data is presented below.



	Quarters Ended
	March 31			June 30			September 30¹			December 31			Full Year
2019	(in thousands, except per share data)
Total revenue	$	679		$	653		$	3,061		$	1,618		$	6,011
Loss from operations	$	(19,071	)	$	(20,515	)	$	(91,401	)	$	(13,087	)	$	(144,074	)
Net loss	$	(23,251	)	$	(23,315	)	$	(82,503	)	$	(24,654	)	$	(153,723	)
Net loss attributable to common shares	$	(25,966	)	$	(26,077	)	$	(85,295	)	$	(27,534	)	$	(164,872	)
Basic and diluted net income/(loss) per common share	$	(0.47	)	$	(0.46	)	$	(1.50	)	$	(0.46	)	$	(2.89	)

In the third quarter of 2019, the Company recorded non-cash impairment charges of $43.8 million and $22.5 million, respectively, to reduce the carrying value of its IPR&D intangible assets and goodwill to zero. The Company also recognized a corresponding income tax benefit of $12.7 million related to the decrease in its deferred tax liability related to the IPR&D intangible assets. See note 8 for more information.



	Quarters Ended
	March 31			June 30			September 30¹			December 31			Full Year
2018	(in thousands, except per share data)
Total revenue	$	1,436		$	1,244		$	1,587		$	1,678		$	5,945
Loss from operations	$	(18,405	)	$	(22,046	)	$	(32,426	)	$	(16,903	)	$	(89,780	)
Net loss	$	(17,429	)	$	3,091		$	(24,473	)	$	(18,249	)	$	(57,060	)
Net income/(loss) attributable to common shares	$	(19,765	)	$	550		$	(27,040	)	$	(20,896	)	$	(67,151	)
Basic and diluted net income/(loss) per common share	$	(0.36	)	$	0.01		$	(0.49	)	$	(0.38	)	$	(1.21	)


¹	In the third quarter of 2018, the Company recorded a $14.8 million non-cash impairment charge to reduce the carrying value of its IPR&D intangible assets, as well as a corresponding income tax benefit of $4.3 million related to the decrease in the related deferred tax liability.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Basis of presentation

Basis of presentation and principles of consolidation

On March 4, 2015, Tekmira completed a business combination pursuant to which OnCore Biopharma, Inc. (“OnCore”), became a wholly-owned subsidiary of Tekmira.

On July 31, 2015, Tekmira changed its corporate name to Arbutus Biopharma Corporation and OnCore changed its corporate name to Arbutus Biopharma, Inc. (“Arbutus Inc.”).

The Company has two wholly-owned subsidiaries as of December 31, 2019: Arbutus Inc. and Arbutus Biopharma US Holdings, Inc., which was formed in 2018.

Consolidation

Foreign currency translation and functional currency conversion

Use of estimates

Cash and cash equivalents

Short-term investments

Investments in marketable securities

Equity method investment

Property and equipment



	Useful Life (Years)
Laboratory equipment		5
Computer and office equipment	2	to	5
Furniture and fixtures		5

Leasehold improvements are depreciated over their estimated useful lives but in no case longer than the lease term, except where lease renewal is reasonably assured.

Impairment of property and equipment

Goodwill and intangible assets

The costs incurred in establishing and maintaining patents for intellectual property developed internally are expensed in the period incurred.

Revenue recognition

Leases and lease inducements

Leases

Research and development costs

Net loss attributable to common shareholders per share

Government grants and refundable investment tax credits

Government grants and tax credits provided for current expenses are included in the determination of income or loss for the year, as a reduction of the expenses to which they relate.

Deferred income taxes

Equity and liability classified stock option awards

Equity-classified stock option awards

The fair value of equity classified stock options is measured at the grant date and is amortized on a straight-line basis over the vesting period.

Liability-classified stock option awards

Preferred Shares

Segment information

Recent accounting pronouncements

Fair value measurements

The Company measures certain financial instruments and other items at fair value.


•	Level 1 inputs are quoted market prices for identical instruments available in active markets.


•	Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability either directly or indirectly. If the asset or liability has a contractual term, the input must be observable for substantially the full term. An example includes quoted market prices for similar assets or liabilities in active markets.


•	Level 3 inputs are unobservable inputs for the asset or liability and will reflect management’s assumptions about market assumptions that would be used to price the asset or liability.

Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Schedule of estimated useful lives of property and equipment

The Company records depreciation using the straight-line method over the estimated useful lives of the capital assets as follows:



	Useful Life (Years)
Laboratory equipment		5
Computer and office equipment	2	to	5
Furniture and fixtures		5

Schedule of computation of basic and diluted net loss per common share

The following table sets out the computation of basic and diluted net loss attributable to common shareholders per share:



	For the year ended December 31,
	2019			2018
	(in thousands, except share and per share amounts)
Numerator:
Allocation of distributable earnings	$	—		$	—
Allocation of undistributable loss	(164,872		)	(67,151		)
Allocation of net loss attributed to common shareholders	$	(164,872	)	$	(67,151	)
Denominator:
Weighted average number of common shares - basic and diluted	57,093,454			55,304,083
Basic and diluted net loss attributable to common shareholders per share	$	(2.89	)	$	(1.21	)

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Schedule of assets and liabilities measured at fair value on a recurring basis



	Level 1		Level 2		Level 3		Total
As of December 31, 2019	(in thousands)
Assets
Cash and cash equivalents	$	31,799	—		—		$	31,799
Investments in marketable securities	59,035		—		—		59,035
Total	$	90,834	$	—	$	—	$	90,834
Liabilities
Liability-classified options	$	—	$	—	$	253	$	253
Contingent consideration	—		—		2,953		2,953
Total	$	—	$	—	$	3,206	$	3,206



	Level 1		Level 2		Level 3		Total
As of December 31, 2018	(in thousands)
Assets
Cash and cash equivalents	$	36,942	—		—		$	36,942
Investments in marketable securities	87,675		—		—		87,675
Total	$	124,617	$	—	$	—	$	124,617
Liabilities
Liability-classified options	$	—	$	—	$	479	$	479
Contingent consideration	—		—		3,126		3,126
Total	$	—	$	—	$	3,605	$	3,605

Schedule of changes in fair value of liability-classified stock options

The following table presents the changes in fair value of the Company’s liability-classified stock option awards:



	Liability at beginning of the period		Fair value of liability-classified options exercised in the period			Increase (decrease) in fair value of liability			Liability at end of the period
	(in thousands)
Year ended December 31, 2019	$	479	$	—		$	(226	)	$	253
Year ended December 31, 2018	$	1,239	$	(93	)	$	(667	)	$	479

Schedule of changes in fair value of contingent consideration

following table presents the changes in fair value of the Company’s contingent consideration:



	Liability at beginning of the period		Increase (decrease) in fair value of liability			Liability at end of the period
	(in thousands)
Year ended December 31, 2019	$	3,126	$	(173	)	$	2,953
Year ended December 31, 2018	$	10,424	$	(7,298	)	$	3,126

Investments in marketable securities (Tables)

12 Months Ended

Dec. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Investments in Marketable Securities

Investments in marketable securities consisted of the following:



	Amortized Cost		Gross Unrealized Gain⁽¹⁾		Gross Unrealized Loss⁽¹⁾			Fair Value
As of December 31, 2019	(in thousands)
Cash equivalents
Money market fund	$	4,106	$	—	$	—		$	4,106
US government agency bonds	1,511		—		—			1,511
US treasury bills	1,499		—		—			1,499
Total	$	7,116	$	—	$	—		$	7,116
Investments in marketable securities
US government agency bonds	$	19,863	$	2	$	(1	)	$	19,864
US treasury bills	15,926		2		$	(1	)	15,927
US government bonds	23,246		—		(2		)	23,244
Total	$	59,035	$	4	$	(4	)	$	59,035

⁽¹⁾Gross unrealized gain (loss) is pre-tax.



	Amortized Cost		Gross Unrealized Gain⁽¹⁾		Gross Unrealized Loss⁽¹⁾		Fair Value
As of December 31, 2018	(in thousands)
Cash equivalents
Individual savings account	$	20,420	$	—	$	—	$	20,420
Total	$	20,420	$	—	$	—	$	20,420
Investments in marketable securities
Canadian guaranteed investment certificates	$	71,483	$	—	$	—	$	71,483
USD term deposit	16,192		—		$	—	$	16,192
Total	$	87,675	$	—	$	—	$	87,675

⁽¹⁾Gross unrealized gain (loss) is pre-tax.

Leases (Tables)

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Schedule of Lease Cost

Weighted average remaining lease term and discount rate were as follows:



	As of December 31, 2019
Weighted-average remaining lease term (years)	7.0
Weighted average discount rate	8.9%

The Company did not include options to extend its lease terms as part of its ROU asset and lease liabilities.

Supplemental cash flow information related to the Company’s operating leases was as follows:



	2019		2018
	(in thousands)
Cash paid for amounts included in the measurement of lease liabilities	$	1,116	$	—

Schedule of Lease Maturity

follows:



	As of December 31, 2019
	(in thousands)
2020	$	657
2021	677
2022	581
2023	598
2024	616
Thereafter	1,423
Total Lease Payments	$	4,552
Less: interest	(1,193		)
Present value of lease payments	$	3,359

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment [Abstract]

Schedule of property and equipment



	Cost		Accumulated depreciation			Net book value
December 31, 2019	(in thousands)
Lab equipment	$	5,511	$	(3,316	)	$	2,195
Leasehold improvements	8,521		(2,152		)	6,369
Computer hardware and software	286		(174		)	112
	$	14,318	$	(5,642	)	$	8,676



	Cost		Accumulated depreciation			Net book value
December 31, 2018	(in thousands)
Lab equipment	$	5,420	$	(2,455	)	$	2,965
Leasehold improvements	9,308		(2,401		)	6,907
Computer hardware and software	2,313		(2,040		)	273
	$	17,041	$	(6,896	)	$	10,145

Accounts Payable and Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2019

Payables and Accruals [Abstract]

Schedule of accounts payable and accrued liabilities

Accounts payable and accrued liabilities are comprised of the following:



	December 31, 2019		December 31, 2018
	(in thousands)
Trade accounts payable	$	2,398	$	3,192
Payroll accruals	2,314		2,341
Research and development accruals	1,433		2,716
Professional fee accruals	809		871
Other accrued liabilities	144		309
Total	$	7,098	$	9,429

Site Consolidation (Tables)

12 Months Ended

Dec. 31, 2019

Restructuring and Related Activities [Abstract]

Schedule of expenses recorded for site consolidation

The following table shows the changes to the site consolidation accrual for the twelve months ended December 31, 2019:



	For the Twelve Months Ended December 31, 2019
	(in thousands)
Accrual Balance December 31, 2018	$	1,331

Employee severance and relocation expense	510
Lease and facility expense	(347		)
Total site consolidation expense	$	163

Amounts paid and adjustments	(1,357		)
Accrual Balance December 31, 2019	$	137

Sale of future royalties (Tables)

12 Months Ended

Dec. 31, 2019

Other Liabilities Disclosure [Abstract]

The table below shows the activity related to the net liability from inception of the Agreement through December 31, 2019:



	Twelve Months Ended December 31, 2019
	(in thousands)
Net liability related to sale of future royalties - beginning balance	$	—
Initial recognition of liability	30,000
Debt discount and issuance costs	(11,451		)
Non-cash interest expense	2,099
Net debt discount and issuance costs	(9,352		)
Non-cash royalty revenue	(1,656		)
Net liability related to sale of future royalties - ending balance	$	18,992

Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of stock option activity

The following table summarizes additional information related to the Company’s equity-classified stock options as of December 31, 2019:



	As of December 31, 2019
Options outstanding and expected to vest
Number of stock options outstanding	8,249,093
Weighted-average exercise price	$	5
Intrinsic value (in $000s)	$	1,001
Weighted-average term remaining	6.9 years
Vested stock options
Number of vested stock options	4,294,649
Weighted-average exercise price	$	5.85
Intrinsic value (in $000s)	$	189
Weighted-average term remaining	5.0 years

Schedule of weighted average option pricing assumptions and the resultant fair values

The weighted average Black-Scholes option-pricing assumptions and the resultant fair values as of December 31, 2019 and December 31, 2018, are presented in the following table:



	December 31, 2019			December 31, 2018
Stock price	$	2.78		$	3.83
Expected average option term	1.6 years			2.2 years
Expected volatility	113.1		%	75.2		%
Expected dividends	—		%	—		%
Risk-free interest rate	1.59		%	2.48		%
Weighted-average fair value per share	$	1.11		$	1.27
Total fair value of vested liability-classified options (in $000s)	$	253		$	479

Schedule of weighted average Black-Scholes option-pricing assumptions and resultant fair values

The assumptions used in the Black-Scholes option-pricing for grants made during the years ended December 31, 2019 and 2018 are as follows:



	December 31, 2019		December 31, 2018
Expected average option term	7.3 years		6.7 years
Expected volatility	75.9	%	75.2	%
Expected dividends	—	%	—	%
Risk-free interest rate	2.27	%	2.81	%

Schedule of allocation of stock-based compensation

Stock-based compensation has been recorded in the consolidated statement of operations and comprehensive income (loss) as follows:



	Year Ended December 31
	2019		2018
	(in thousands)
Research and development	$	2,971	$	2,670
General and administrative	3,828		3,337
Total	$	6,799	$	6,007

OnCore Option Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of stock option activity

The following table summarizes additional information related to the OnCore stock options as of December 31, 2019:



	As of December 31, 2019
Vested stock options
Intrinsic value (in $000s)	$	222,248
Weighted-average term remaining	4.9 years

Schedule of option activity

The following table summarizes activity related to the OnCore stock options for the year ended December 31, 2019:



	Stock Options Vested and Outstanding
	Number of OnCore Options		Number of Equivalent Company Common Shares		Weighted-Average Exercise Price
Balance as of December 31, 2018	139,290		140,273		$	0.56
Options exercised	(40,000	)	(40,282	)	$	0.58
Options forfeit, canceled or expired	—		—		$	—
Balance as of December 31, 2019	99,290		99,991		$	0.56

Liability classified stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of stock option activity

The following table summarizes activity related to the Company’s liability-classified stock options for the year ended December 31, 2019:



	Stock Options Vested and Outstanding
	Number		Weighted-Average Exercise Price
Balance as of December 31, 2018	377,500		$	5.81
Options exercised	—		$	—
Options forfeit, canceled or expired	(150,000	)	$	7.01
Balance as of December 31, 2019	227,500		$	5.49

The following table summarizes additional information related to the Company’s liability-classified stock options as of December 31, 2019:



	As of December 31, 2019
Options outstanding and expected to vest
Intrinsic value (in $000s)	$	96
Weighted-average term remaining	1.6 years

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of effective income tax rate reconciliation



	Year ended December 31,
	2019			2018
	(in thousands)
Computed taxes (benefits) at Canadian federal and provincial tax rates	$	(44,922	)	$	(16,563	)
Difference between statutory rate and foreign rate	8,356			—
Adjustments to prior year	(525		)	—
Permanent and other differences	3,458			(2,328		)
Change in valuation allowance - other	19,078			13,062
Difference due to income taxed at foreign rates	(3,343		)	(138		)
Stock-based compensation	523			1,685
Impairment of goodwill	4,719			—
Deferred income tax benefit	$	(12,656	)	$	(4,282	)

Schedule of components of deferred tax assets

Significant components of the Company’s deferred tax assets and liabilities are shown below:



	As of December 31,
	2019			2018
	(in thousands)
Deferred tax assets (liabilities):
Non-capital loss carryforwards	$	59,956		$	51,575
Research and development deductions	16,349			15,803
Book amortization in excess of tax	(914		)	(608		)
Share issue costs	202			307
Revenue recognized for tax purposes in excess of revenue recognized for accounting purposes	5,128			—
Tax value in excess of accounting value in lease inducements	705			147
Federal investment tax credits	7,325			9,686
Provincial investment tax credits	4,535			3,955
In-process research and development	—			(12,664		)
Upfront license fees	236			283
Equity accounted for investment	3,038			37
Other	6,202			2,503
Total deferred tax assets (liabilities)	102,762			71,024
Valuation allowance	(102,762		)	(83,685		)
Net deferred tax assets (liabilities)	$	—		$	(12,661	)

Interim Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Schedule of interim financial data (unaudited)



	Quarters Ended
	March 31			June 30			September 30¹			December 31			Full Year
2019	(in thousands, except per share data)
Total revenue	$	679		$	653		$	3,061		$	1,618		$	6,011
Loss from operations	$	(19,071	)	$	(20,515	)	$	(91,401	)	$	(13,087	)	$	(144,074	)
Net loss	$	(23,251	)	$	(23,315	)	$	(82,503	)	$	(24,654	)	$	(153,723	)
Net loss attributable to common shares	$	(25,966	)	$	(26,077	)	$	(85,295	)	$	(27,534	)	$	(164,872	)
Basic and diluted net income/(loss) per common share	$	(0.47	)	$	(0.46	)	$	(1.50	)	$	(0.46	)	$	(2.89	)



	Quarters Ended
	March 31			June 30			September 30¹			December 31			Full Year
2018	(in thousands, except per share data)
Total revenue	$	1,436		$	1,244		$	1,587		$	1,678		$	5,945
Loss from operations	$	(18,405	)	$	(22,046	)	$	(32,426	)	$	(16,903	)	$	(89,780	)
Net loss	$	(17,429	)	$	3,091		$	(24,473	)	$	(18,249	)	$	(57,060	)
Net income/(loss) attributable to common shares	$	(19,765	)	$	550		$	(27,040	)	$	(20,896	)	$	(67,151	)
Basic and diluted net income/(loss) per common share	$	(0.36	)	$	0.01		$	(0.49	)	$	(0.38	)	$	(1.21	)


¹	In the third quarter of 2018, the Company recorded a $14.8 million non-cash impairment charge to reduce the carrying value of its IPR&D intangible assets, as well as a corresponding income tax benefit of $4.3 million related to the decrease in the related deferred tax liability.

Significant Accounting Policies - Narrative (Details)	3 Months Ended	12 Months Ended
Significant Accounting Policies - Narrative (Details)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) subsidiary shares	Dec. 31, 2018 USD ($) shares	May 30, 2008
Business Acquisition [Line Items]
Wholly-owned subsidiaries \| subsidiary		2
Impairment of goodwill (note 8)		$ 43,836,000	$ 14,811,000
Investment in Genevant		0	22,224,000
Tax benefit related to decrease in deferred tax liability for indefinite delay of further development		12,700,000
Goodwill, Impairment Loss, Net of Tax	$ 22,500,000
Goodwill		$ 0	$ 22,471,000
Anti-dilutive common shares excluded from calculation of income per common share (in shares) \| shares		28,357,105	24,717,000
Interest rate on restricted investment		8.75%
Convertible Preferred Shares
Business Acquisition [Line Items]
Issuance of Preferred Shares, net of issuance cost (in shares) \| shares			664,000
Stock Option
Business Acquisition [Line Items]
Anti-dilutive common shares excluded from calculation of income per common share (in shares) \| shares		8,925,084
Convertible Preferred Shares
Business Acquisition [Line Items]
Anti-dilutive common shares excluded from calculation of income per common share (in shares) \| shares		19,432,021
PADCo. \| Monsanto
Business Acquisition [Line Items]
Business acquisition, percentage of outstanding shares acquired				100.00%
Genevant Sciences Corporation [Member]
Business Acquisition [Line Items]
Equity Method Investment, Other than Temporary Impairment		$ 7,600,000
In Process Research and Development
Business Acquisition [Line Items]
Impairment of goodwill (note 8)		43,800,000
Tax benefit related to decrease in deferred tax liability for indefinite delay of further development		$ 12,700,000

Significant Accounting Policies - Estimated Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Laboratory equipment
Property, Plant and Equipment [Line Items]
Useful Life (Years)		5 years
Computer and office equipment \| Minimum
Property, Plant and Equipment [Line Items]
Useful Life (Years)	5 years	2 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful Life (Years)		5 years

Significant Accounting Policies - Computation of Basic and Diluted Net Income (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended							9 Months Ended	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Allocation of distributable earnings									$ 11,149	$ 10,091
Allocation of earnings (loss) attributed to shareholders	$ (27,534)	$ (85,295)	$ (26,077)	$ (25,966)	$ (20,896)	$ 550	$ (19,765)	$ (27,040)	$ (164,872)	$ (67,151)
Earnings Per Share, Basic and Diluted					$ (0.38)	$ 0.01	$ (0.36)	$ (0.49)	$ (2.89)	$ (1.21)
Common Shares
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Allocation of distributable earnings									$ 0	$ 0
Allocation of undistributable loss									(164,872)	(67,151)
Allocation of earnings (loss) attributed to shareholders									$ (164,872)	$ (67,151)
Weighted average number of shares - basic diluted (in shares)									57,093,454	55,304,083
Earnings Per Share, Basic and Diluted									$ (2.89)	$ (1.21)

Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair value of contingent consideration	$ 2,953	$ 3,126	$ 10,424
Decrease in fair value of contingent consideration	$ 173	$ 7,298

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability-classified options
Contingent consideration	$ 253	$ 479
Total	2,953	3,126	$ 10,424
Fair Value, Measurements, Recurring
Assets
Cash and cash equivalents	31,799	36,942
Investments in marketable securities	59,035	87,675
Total	90,834	124,617
Liability-classified options
Contingent consideration	253	479
Total	2,953	3,126
Total	3,206	3,605
Fair Value, Measurements, Recurring \| Level 1
Assets
Cash and cash equivalents	31,799	36,942
Investments in marketable securities	59,035	87,675
Total	90,834	124,617
Liability-classified options
Total	0	0
Total	0	0
Fair Value, Measurements, Recurring \| Level 2
Assets
Cash and cash equivalents	0	0
Investments in marketable securities	0	0
Total	0	0
Liability-classified options
Total	0	0
Total	0	0
Fair Value, Measurements, Recurring \| Level 3
Assets
Cash and cash equivalents	0	0
Investments in marketable securities	0	0
Total	0	0
Liability-classified options
Contingent consideration	253	479
Total	2,953	3,126
Total	$ 3,206	$ 3,605

Fair Value Measurements - Changes in Fair Value of Liabilities-Classified as Stock Option (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis [Roll Forward]
Liability at beginning of the period	$ 479
Liability at end of the period	253	$ 479
Liability classified stock options
Fair Value, Liabilities Measured on Recurring Basis [Roll Forward]
Liability at beginning of the period	479	1,239
Fair value of liability-classified options exercised in the period	0	93
Increase (decrease) in fair value of liability	(226)	(667)
Liability at end of the period	$ 253	$ 479

Fair Value Measurements - Changes in Fair Value of Contingent Consideration (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis [Roll Forward]
Liability at beginning of the period	$ 3,126	$ 10,424
Increase (decrease) in fair value of contingent consideration	(173)	(7,298)
Liability at end of the period	$ 2,953	$ 3,126

Equity method investment - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Apr. 11, 2018	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Ownership interest in equity method investment			40.00%
Net equity investment gain or loss			$ (22,522)	$ 19,557
Equity Method Investments			0	22,224
Genevant
Schedule of Equity Method Investments [Line Items]
Initial investment in Genevant	$ 600
Ownership interest in equity method investment	50.00%
Gain on property contribution to equity method investment		$ 24,900
Goodwill transfer to equity method investment	$ 1,893
Gain on investments			14,900	$ 5,600
Equity Method Investment, Other than Temporary Impairment			$ 7,600
Genevant \| Roivant Sciences Ltd
Schedule of Equity Method Investments [Line Items]
Initial investment in Genevant	37,500
Initial capital contribution	22,500
Commitment to contribute to equity method investment	$ 15,000

Investments in marketable securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 7,116	$ 20,420
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	7,116	20,420
Cash Equivalents \| Money Market Funds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,106
Gross Unrealized Gain	0
Gross Unrealized Loss	0
Fair Value	4,106
Cash Equivalents \| US Government Agency Bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,511
Gross Unrealized Gain	0
Gross Unrealized Loss	0
Fair Value	1,511
Cash Equivalents \| US Treasury Bill Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,499
Gross Unrealized Gain	0
Gross Unrealized Loss	0
Fair Value	1,499
Cash Equivalents \| Individual Savings Account
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		20,420
Gross Unrealized Gain		0
Gross Unrealized Loss		0
Fair Value		20,420
Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	59,035	87,675
Gross Unrealized Gain	4	0
Gross Unrealized Loss	(4)	0
Fair Value	59,035	87,675
Marketable Securities \| US Government Agency Bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	19,863
Gross Unrealized Gain	2
Gross Unrealized Loss	(1)
Fair Value	19,864
Marketable Securities \| US Treasury Bill Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	15,926
Gross Unrealized Gain	2
Gross Unrealized Loss	(1)
Fair Value	15,927
Marketable Securities \| US Government Bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	23,246
Gross Unrealized Gain	0
Gross Unrealized Loss	(2)
Fair Value	$ 23,244
Marketable Securities \| Canadian Guaranteed Investment Certificates
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		71,483
Gross Unrealized Gain		0
Gross Unrealized Loss		0
Fair Value		71,483
Marketable Securities \| USD Term Deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		16,192
Gross Unrealized Gain		0
Gross Unrealized Loss		0
Fair Value		$ 16,192

Leases (Details) $ in Millions	12 Months Ended
Leases (Details) $ in Millions	Dec. 31, 2019 USD ($) lease renewal_option	Dec. 31, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Number of operating leases \| lease	2
Operating lease expense	$ 1.2
Fixed lease payment	0.9
Variable lease payment	0.3
Stright-line fixed expense		$ 1.4
Sublease income	$ 0.2	$ 0.2
Corporate Headquarters Located 701 Veterans Circle, Warminster, Pennsylvania
Lessee, Lease, Description [Line Items]
Number of renewal options \| renewal_option	2
Renewal term	5 years
Discount rate	9.00%
Offices Located at 626 Jacksonville Rd., Warminster, Pennsylvania
Lessee, Lease, Description [Line Items]
Discount rate	7.60%
Genevant \| Burnaby Facility
Lessee, Lease, Description [Line Items]
Discount rate	5.00%

Leases - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
Leases - Lease Cost (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Weighted-average remaining lease term (years)	7 years 1 day
Weighted average discount rate	8.90%
Cash paid for amounts included in the measurement of lease liabilities	$ 1,116	$ 0

Leases - Maturity of Lease Liability (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019
Leases [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	$ 657
Lessee, Operating Lease, Liability, Payments, Due Year Two		$ 677
2022		581
Lessee, Operating Lease, Liability, Payments, Due Year Four		598
2023		$ 616
Thereafter	1,423
Total Lease Payments	4,552
Less: interest	(1,193)
Present value of lease payments	$ 3,359

Property and Equipment (Details) - USD ($)	12 Months Ended
Property and Equipment (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Cost	$ 14,318,000	$ 17,041,000
Accumulated depreciation	(5,642,000)	(6,896,000)
Property and equipment, net of accumulated depreciation	8,676,000	10,145,000
Disposed equipment, furniture, and leasehold improvements	3,400,000
Net book value of disposal assets	100,000
Lab equipment
Property, Plant and Equipment [Line Items]
Cost	5,511,000	5,420,000
Accumulated depreciation	(3,316,000)	(2,455,000)
Property and equipment, net of accumulated depreciation	2,195,000	2,965,000
Leasehold improvements
Property, Plant and Equipment [Line Items]
Cost	8,521,000	9,308,000
Accumulated depreciation	(2,152,000)	(2,401,000)
Property and equipment, net of accumulated depreciation	6,369,000	6,907,000
Computer hardware and software
Property, Plant and Equipment [Line Items]
Cost	286,000	2,313,000
Accumulated depreciation	(174,000)	(2,040,000)
Property and equipment, net of accumulated depreciation	$ 112,000	$ 273,000

Intangible Assets and Goodwill - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Indefinite-lived Intangible Assets [Line Items]
Impairment of goodwill (note 8)	$ 43,836,000	$ 14,811,000
Intangible assets	0	43,836,000
Tax benefit related to decrease in deferred tax liability for indefinite delay of further development	12,700,000
Income tax benefit corresponding to impairment charge	12,656,000	4,282,000
Impairment of goodwill	22,471,000	0
Goodwill	0	$ 22,471,000
Intangible Assets, Net (Including Goodwill)	0
In Process Research and Development, cccDNA Sterilizers [Member]
Indefinite-lived Intangible Assets [Line Items]
Impairment of goodwill (note 8)	43,800,000
Intangible assets	$ 0

Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Trade accounts payable	$ 2,398	$ 3,192
Payroll accruals	2,314	2,341
Research and development accruals	1,433	2,716
Professional fee accruals	809	871
Other accrued liabilities	144	309
Accounts payable and accrued liabilities	$ 7,098	$ 9,429

Site Consolidation (Details) - USD ($) $ in Thousands	12 Months Ended
Site Consolidation (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2019
Description of expense
Restructuring Reserve	$ 137
Total site consolidation expense	156	$ 4,797
Accrual Balance December 31, 2018
Description of expense
Restructuring Reserve		$ 1,331
Employee severance and relocation expense
Description of expense
Total site consolidation expense	510
Lease and facility expense
Description of expense
Total site consolidation expense	(347)
Total site consolidation expense
Description of expense
Total site consolidation expense	163
Facility closing
Restructuring Cost and Reserve [Line Items]
Expected total cost of site consolidation			$ 5,000
Description of expense
Total site consolidation expense	4,900
Amounts paid and adjustments	$ (1,357)

Loan Payable (Details) - USD ($)	Dec. 27, 2016	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Restricted investment	$ 12,601,000
Restricted investment, term	2 years
Investments in marketable securities		$ 59,035,000		$ 87,675,000
Wells Fargo
Debt Instrument [Line Items]
Investments in marketable securities			$ 12,601,000
Loans payable \| Promissory note with Wells Fargo \| Wells Fargo
Debt Instrument [Line Items]
Loan payable	$ 12,001,000
Loans payable \| Promissory note with Wells Fargo \| LIBOR
Debt Instrument [Line Items]
Fixed component of interest rate	1.25%

Sale of future royalties (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Sale of future royalties (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2019	Jul. 02, 2019
Other Liabilities Disclosure [Abstract]
Liability Related To Sale Of Future Royalties		$ 18,992	$ 0
Liability From Sale Of Future Royalties, Additions	$ 30,000
Liability From Sale Of Future Royalties, Discounts And Issuance Costs		(11,451)
Liability From Sale Of Future Royalties, Non Cash Royalty Income		(1,656)
Liability From Sale Of Future Royalties, Non Cash Expense		$ 2,099

Sale of future royalties - Narrative (Details) - USD ($) $ in Thousands			12 Months Ended
	Jul. 02, 2019	Jan. 01, 2019	Dec. 31, 2019	Dec. 31, 2018
Other Liabilities Disclosure [Line Items]
Royalty guarantees commitments percentage			2.50%
Non Cash Royalty Revenue Related To Sale Of Future Royalties			$ 1,656	$ 0
Non Cash Royalty Expense Related To Sale Of Future Royalties			2,099	$ 0
OMERS
Other Liabilities Disclosure [Line Items]
Royalty Interest Sold, Percentage Of Sales, Annual Revenue Threshold Of Highest Tier	$ 500,000
Gross Proceeds From Royalty Interest Sold		$ 20,000
Royalty Interest Sold, Maximum Royalties For Buyer	$ 30,000
Royalty guarantees commitments percentage	100.00%
Royalty Payable	$ 30,000
Transaction Costs Related To Sale Of Future Royalties	$ 1,500
Effective Annual Interest Rate Of Royalty Liability	22.00%
Non Cash Royalty Revenue Related To Sale Of Future Royalties			(1,700)
Non Cash Royalty Expense Related To Sale Of Future Royalties			$ 2,100
Minimum \| OMERS
Other Liabilities Disclosure [Line Items]
Royalty, Percentage of Interest Sold	1.00%
Maximum \| OMERS
Other Liabilities Disclosure [Line Items]
Royalty, Percentage of Interest Sold	2.33%

Contingencies and Commitments - Narrative (Details) $ in Thousands			12 Months Ended			53 Months Ended
	Aug. 20, 2019 USD ($)	Jan. 16, 2015 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 CAD ($)	Dec. 31, 2018 USD ($)	Mar. 31, 2004 USD ($)	Mar. 31, 2004 CAD ($)	Dec. 31, 2019 CAD ($)	Dec. 31, 2017 USD ($)	Oct. 31, 2014 USD ($)
Contingencies and Commitments [Line Items]
Percent of costs funded by TPC						27.00%	27.00%
Maximum contribution for product						$ 7,179,000	$ 9,330
Cumulative contribution for product			$ 2,714,000	$ 3,702
Royalty guarantees commitments percentage			2.50%	2.50%
Business Combination, Contingent Consideration, Liability, Noncurrent			$ 2,953,000		$ 3,126,000				$ 10,424,000
Arbutus Inc. \| Enantigen
Contingencies and Commitments [Line Items]
Business combination, high end of payment upon achievement of certain triggering events										$ 21,000,000
Business combination, regulatory, development and sales milestone payments estimated fair value										3,000,000
Arbitration with the University of British Columbia
Contingencies and Commitments [Line Items]
Loss contingency, damages sought for allegedly unpaid royalties		$ 3,500,000	10,900,000
Payments for legal settlements	$ 5,900,000
Loss contingency, loss in period			6,300,000
Litigation Settlement Interest	$ 2,600,000
Amount awarded to other party			5,900,000
Blumberg and Drexel \| Arbutus Inc.
Contingencies and Commitments [Line Items]
Development and regulatory milestones payment per licensed compound series, maximum										102,500,000
Maximum royalty payment										$ 1,000,000
Royalty
Contingencies and Commitments [Line Items]
Collaborations and contracts			296,800		154,000
Royalties paid or accrued			100,000
Contractual obligation			2,682,000					$ 3,659
Minimum \| Arbitration with the University of British Columbia
Contingencies and Commitments [Line Items]
Estimate of possible loss			400,000
Fair Value, Measurements, Recurring
Contingencies and Commitments [Line Items]
Business Combination, Contingent Consideration, Liability, Noncurrent			2,953,000		$ 3,126,000
Fair Value, Measurements, Recurring \| Blumberg and Drexel \| Enantigen
Contingencies and Commitments [Line Items]
Business Combination, Contingent Consideration, Liability, Noncurrent			$ 0

Collaborations, Contracts and Licensing Agreements - Narrative (Details)	3 Months Ended							9 Months Ended	12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2012 USD ($)	Apr. 11, 2018	May 06, 2006 chemotherapy_products
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Non Cash Royalty Revenue Related To Sale Of Future Royalties									$ 1,656,000	$ 0
Total revenue	$ 1,618,000	$ 3,061,000	$ 653,000	$ 679,000	$ 1,678,000	$ 1,244,000	$ 1,436,000	$ 1,587,000	6,011,000	5,945,000
Number of chemotherapy products with worldwide licenses \| chemotherapy_products													3
OMERS
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Non Cash Royalty Revenue Related To Sale Of Future Royalties									(1,700,000)
Total revenue									(200,000)
Talon Therapeutics
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Potential contract funding amount											$ 18,000,000
Marqibo Commercial Sales
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue									605,000	158,000
Contracts revenue											$ 1,000,000
License \| Gritstone
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue									1,819,000	4,318,000
Development milestone payment									2,500,000
License \| Gritstone, Milestone
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue									1,250,000
License \| Acuitas Therapeutics Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total revenue									$ 1,931,000	$ 1,009,000
Genevant \| License \| Gritstone
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Equity method investment, percentage or revenue entitled												50.00%

Shareholders' Equity (Details) - USD ($)				12 Months Ended
Shareholders' Equity (Details) - USD ($)	Jan. 12, 2018	Oct. 16, 2017	Oct. 02, 2017	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2020	Dec. 31, 2017
Class of Stock [Line Items]
Proceeds from issuance of common stock				$ 18,601,000	$ 0
Issuance of common shares in conjunction with the private offering, net of issuance costs				$ 18,601,000
Shares price (in USD per share)				$ 2.78	$ 3.83
Proceeds from sale of preferred shares, net of issuance costs				$ 0	$ 66,265,000
Number of warrant outstanding (in shares)				0
Roivant
Class of Stock [Line Items]
Noncontrolling interest, ownership percentage by owners after conversion			42.00%
Noncontrolling interest, maximum ownership percentage by noncontrolling owners			49.99%
Proceeds from sale of preferred shares, net of issuance costs	$ 66,400,000	$ 50,000,000
Common Shares \| Sale Agreement \| Jefferies LLC
Class of Stock [Line Items]
Aggregate share sales price				$ 50,000,000.0		$ 50,000,000.0
Number of shares issued under agreement (in shares)				9,138,232
Proceeds from issuance of common stock				$ 19,500,000
Convertible Preferred Stock \| Roivant
Class of Stock [Line Items]
Issuance of common shares in conjunction with the private offering, net of issuance costs			$ 116,400,000
Preferred stock, par value (USD per share)			$ 7.13
Premium percentage on closing stock price			15.00%
Shares price (in USD per share)			$ 6.20
Preferred dividend percentage			8.75%		8.75%
Noncontrolling interest, investment commitment period			4 years
Preferred Shares
Class of Stock [Line Items]
Shares issued				1,164,000	1,164,000		500,000
Issuance of common shares in conjunction with the private offering, net of issuance costs					$ 66,265,000

Stock-based Compensation - Narrative (Details) $ in Thousands		1 Months Ended	12 Months Ended
	Mar. 04, 2015 USD ($) shares	Feb. 28, 2019 executive_officers shares	Dec. 31, 2019 USD ($) executive_officers shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2013 executive_officers shares	May 19, 2016 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized (in shares)			2,424,703
Expected average option term	8 years		1 year 7 months	2 years 2 months
Number of executive officers granted options with new appointments \| executive_officers					2
Risk-free interest rate			1.59%	2.48%
Stock-based compensation expense \| $			$ 6,799	$ 6,007
Unearned compensation expense \| $			$ 6,846
Unearned compensation expense, recognition period			25 months
Liability classified stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)			227,500	377,500
Options exercisable, intrinsic value \| $			$ 71
Risk-free interest rate			0
2016 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock-based compensation awards approved to be issued (in shares)						12,790,202
2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected average option term			10 years
Designated Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)			150,000
Options granted (in shares)			0		200,000
Number of executive officers granted options with new appointments \| executive_officers		1	1
Options expired (in shares)		150,000
Arbutus Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected average option term			7 years 3 months	6 years 8 months
Options exercisable, intrinsic value \| $			$ 100	$ 1,142
Risk-free interest rate			2.27%	2.81%
OnCore Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock-based compensation awards approved to be issued (in shares)	184,332
Number of options outstanding (in shares)			99,290	139,290
Options exercisable, intrinsic value \| $			$ 138	$ 285
Fair value of consideration issued \| $	$ 3,300
Risk-free interest rate	0.97%
Business acquisition, fair value amount attributed as pre-combination service and included as part of acquisition consideration \| $	$ 1,100
Business acquisition, post-combination attribution recognized as compensation expense \| $	$ 2,200
OnCore Option Plan \| Measurement Input, Option Volatility [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.78
OnCore Option Plan \| Measurement Input, Expected Dividend Rate [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0
OnCore Option Plan \| Equivalent number of Company common shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)			99,991	140,273
Collier Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)					1,112,000
Minimum \| 2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period			3 years
Maximum \| 2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period			4 years
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)			8,576,584
Stock Option \| Arbutus Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (in shares)			8,249,093	6,331,088
Options granted (in shares)			3,018,000

Stock-based Compensation - Stock Option Activity (Details)	12 Months Ended
	Dec. 31, 2019 $ / shares shares
OnCore Option Plan
Number of optioned common shares
Balance - Number of optioned common shares (in shares)	139,290
Options exercised (in shares)	(40,000)
Options forfeited, canceled or expired (in shares)	0
Balance - Number of optioned common shares (in shares)	99,290
Weighted average exercise price
Balance - Weighted average exercise price (in CAD and USD per share) \| $ / shares	$ 0.56
Options exercised - Weighted average exercise price (in CAD and USD per share) \| $ / shares	0.58
Options forfeited, canceled or expired - Weighted average exercise price (in CAD and USD per share) \| $ / shares	0.00
Balance - Weighted average exercise price (in CAD and USD per share) \| $ / shares	$ 0.56
Arbutus Plans
Number of optioned common shares
Options forfeited, canceled or expired (in shares)	(1,016,995)
Weighted average exercise price
Options forfeited, canceled or expired - Weighted average exercise price (in CAD and USD per share) \| $ / shares	$ 6.98
Stock Option
Number of optioned common shares
Balance - Number of optioned common shares (in shares)	8,576,584
Stock Option \| Arbutus Plans
Number of optioned common shares
Balance - Number of optioned common shares (in shares)	6,331,088
Options granted (in shares)	3,018,000
Options exercised (in shares)	(83,000)
Options vested (in shares)	0
Balance - Number of optioned common shares (in shares)	8,249,093
Weighted average exercise price
Balance - Weighted average exercise price (in CAD and USD per share) \| $ / shares	$ 6.05
Options granted - Weighted average exercise price (in CAD and USD per share) \| $ / shares	3.41
Options exercised - Weighted average exercise price (in CAD and USD per share) \| $ / shares	3.25
Options vested (USD per share) \| $ / shares	0.00
Balance - Weighted average exercise price (in CAD and USD per share) \| $ / shares	$ 5.00
Vested Stock Options \| Arbutus Plans
Number of optioned common shares
Balance - Number of optioned common shares (in shares)	2,620,542
Options granted (in shares)	0
Options exercised (in shares)	(83,000)
Options forfeited, canceled or expired (in shares)	(477,848)
Options vested (in shares)	(2,234,955)
Balance - Number of optioned common shares (in shares)	4,294,649
Non-Vested Stock Options \| Arbutus Plans
Number of optioned common shares
Balance - Number of optioned common shares (in shares)	3,710,546
Options granted (in shares)	3,018,000
Options exercised (in shares)	0
Options forfeited, canceled or expired (in shares)	(539,147)
Options vested (in shares)	(2,234,955)
Balance - Number of optioned common shares (in shares)	3,954,444
Weighted average exercise price
Balance - Weighted average exercise price (in CAD and USD per share) \| $ / shares	$ 3.39
Options granted - Weighted average exercise price (in CAD and USD per share) \| $ / shares	2.43
Options exercised - Weighted average exercise price (in CAD and USD per share) \| $ / shares	0.00
Options forfeited, canceled or expired - Weighted average exercise price (in CAD and USD per share) \| $ / shares	3.24
Options vested (USD per share) \| $ / shares	3.10
Balance - Weighted average exercise price (in CAD and USD per share) \| $ / shares	$ 2.86
Equivalent number of Company common shares \| OnCore Option Plan
Number of optioned common shares
Balance - Number of optioned common shares (in shares)	140,273
Options exercised (in shares)	(40,282)
Options forfeited, canceled or expired (in shares)	0
Balance - Number of optioned common shares (in shares)	99,991

Stock-based Compensation - Stock Options Outstanding (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stock Option
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options outstanding (in shares)	8,249,093
Options outstanding, Weighted average exercise price (in USD per share)	$ 5
Intrinsic value (in $000s)	$ 1,001
Weighted average remaining contractual life (years)	6 years 11 months
Vested Stock Options
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options outstanding (in shares)	4,294,649
Options outstanding, Weighted average exercise price (in USD per share)	$ 6
Intrinsic value (in $000s)	$ 189
Weighted average remaining contractual life (years)	5 years
Liability classified stock options
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, Weighted average exercise price (in USD per share)	$ 5.49	$ 5.81
Intrinsic value (in $000s)	$ 96
Weighted average remaining contractual life (years)	1 year 6 months 34 days
OnCore Option Plan
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, Weighted average exercise price (in USD per share)	$ 0.56	$ 0.56
Intrinsic value (in $000s)	$ 222
Weighted average remaining contractual life (years)	4 years 11 months

Stock-based Compensation - Valuation Assumptions for Stock Options (Details)		12 Months Ended
	Mar. 04, 2015	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected average option term	8 years	1 year 7 months	2 years 2 months
Expected volatility		113.10%	75.20%
Expected dividends		0.00%	0.00%
Risk-free interest rate		1.59%	2.48%
Arbutus Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected average option term		7 years 3 months	6 years 8 months
Expected volatility		75.90%	75.20%
Expected dividends		0.00%	0.00%
Risk-free interest rate		2.27%	2.81%

Stock-based Compensation - Valuation Assumptions for Liability-Classified Options (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Mar. 04, 2015	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares price (in USD per share)		$ 2.78	$ 3.83
Expected average option term	8 years	1 year 7 months	2 years 2 months
Expected volatility		113.10%	75.20%
Expected dividends		0.00%	0.00%
Risk-free interest rate		1.59%	2.48%
Weighted average fair value per share of options outstanding (in USD per share)		$ 1.11	$ 1.27
Total fair value of vested liability-classified options (in $000s)		$ 253	$ 479
Liability classified stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of vested liability-classified options (in $000s)		$ 253	$ 479	$ 1,239

Stock-based Compensation - Stock Option Activity for Liability-Classified Options (Details) - Liability classified stock options - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2019
Number of optioned common shares
Balance - Number of optioned common shares (in shares)	377,500	377,500
Options exercised (in shares)		0
Options forfeited, canceled or expired (in shares)	(150,000)
Balance - Number of optioned common shares (in shares)		227,500
Weighted average exercise price
Balance - Weighted average exercise price (in CAD and USD per share)	$ 5.81	$ 5.81
Options exercised - Weighted average exercise price (in CAD and USD per share)		0.00
Options forfeited, canceled or expired - Weighted average exercise price (in CAD and USD per share)		7.01
Balance - Weighted average exercise price (in CAD and USD per share)		$ 5.49

Stock-based Compensation - Outstanding Options Under the OnCore Option Plan (Details) - OnCore Option Plan	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Number of optioned common shares
Balance - Number of optioned common shares (in shares)	139,290
Options exercised (in shares)	(40,000)
Options forfeited, canceled or expired (in shares)	0
Balance - Number of optioned common shares (in shares)	99,290
Weighted average exercise price
Balance - Weighted average exercise price (in CAD and USD per share) \| $ / shares	$ 0.56
Options exercised - Weighted average exercise price (in CAD and USD per share) \| $ / shares	0.58
Options forfeited, canceled or expired - Weighted average exercise price (in CAD and USD per share) \| $ / shares	0.00
Balance - Weighted average exercise price (in CAD and USD per share) \| $ / shares	$ 0.56
Equivalent number of Company common shares
Number of optioned common shares
Balance - Number of optioned common shares (in shares)	140,273
Options exercised (in shares)	(40,282)
Options forfeited, canceled or expired (in shares)	0
Balance - Number of optioned common shares (in shares)	99,991

Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 6,799	$ 6,007
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,971	2,670
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 3,828	$ 3,337

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Canadian federal and provincial income tax rate	27.00%	27.00%
Research and development credits	$ 3,897	$ 4,265
Scientific research and experimental development expenditures available for indefinite carry-forward	59,956	51,575
Deferred tax assets, operating loss carryforwards, subject to expiration	11,726	11,040
Investment tax credit carryforward
Income Taxes [Line Items]
Investment tax credits available to reduce Canadian federal income taxes	10,035	8,784
Investment tax credits available to reduce provincial income taxes	4,535	4,002
Research tax credit carryforward
Income Taxes [Line Items]
Scientific research and experimental development expenditures available for indefinite carry-forward	60,553	61,493
Deferred tax assets, operating loss carryforwards, subject to expiration	$ 164,932	$ 182,256

Income Taxes - Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Computed taxes (benefits) at Canadian federal and provincial tax rates	$ (44,922)	$ (16,563)
Difference between statutory rate and foreign rate	8,356	0
Permanent and other differences	3,458	(2,328)
Change in valuation allowance - other	19,078	13,062
Difference due to income taxed at foreign rates	(3,343)	(138)
Stock-based compensation	523	1,685
Impairment of goodwill	4,719	0
Deferred income tax benefit	$ (12,656)	$ (4,282)

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Components of Deferred Tax Assets [Line Items]
Non-capital loss carryforwards	$ 59,956	$ 51,575
Research and development deductions	16,349	15,803
Book amortization in excess of tax	(914)	(608)
Share issue costs	202	307
Revenue recognized for tax purposes in excess of revenue recognized for accounting purposes	5,128	0
Tax value in excess of accounting value in lease inducements	705	147
In-process research and development	0	(12,664)
Upfront license fees	236	283
Equity accounted for investment	3,038	37
Other	6,202	2,503
Total deferred tax assets (liabilities)	102,762	71,024
Valuation allowance	(102,762)	(83,685)
Net deferred tax assets (liabilities)	0	(12,661)
Federal
Components of Deferred Tax Assets [Line Items]
Investment tax credits	7,325	9,686
Provincial
Components of Deferred Tax Assets [Line Items]
Investment tax credits	$ 4,535	$ 3,955

Related Party Transactions (Details) $ in Thousands	12 Months Ended
Related Party Transactions (Details) $ in Thousands	Dec. 31, 2019 USD ($) ft²	Dec. 31, 2018 USD ($)
Roivant Sciences Ltd \| Co-venturer \| Research and development services
Related Party Transaction [Line Items]
Expenses from transactions with related party		$ 644
Genevant \| Equity Method Investee \| Research and development services
Related Party Transaction [Line Items]
Expenses from transactions with related party		398
Genevant \| Equity Method Investee \| Administrative and transitional services
Related Party Transaction [Line Items]
Income from related party	$ 106	226
Genevant \| Equity Method Investee \| Sublease Burnaby facility
Related Party Transaction [Line Items]
Income from related party	$ 180	$ 180
Area of sublease facility \| ft²	17,900

Interim Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended							9 Months Ended	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 1,618	$ 3,061	$ 653	$ 679	$ 1,678	$ 1,244	$ 1,436	$ 1,587	$ 6,011	$ 5,945
Loss from operations	(13,087)	(91,401)	(20,515)	(19,071)	(16,903)	(22,046)	(18,405)	(32,426)	(144,074)	(89,780)
Net loss	(24,654)	(82,503)	(23,315)	(23,251)	(18,249)	3,091	(17,429)	(24,473)	(153,723)	(57,060)
Net loss attributable to common shares	$ (27,534)	$ (85,295)	$ (26,077)	$ (25,966)	$ (20,896)	$ 550	$ (19,765)	$ (27,040)	$ (164,872)	$ (67,151)
Basic net income/(loss) per common share (in USD per share)	$ (0.46)	$ (1.50)	$ (0.46)	$ (0.47)
Earnings Per Share, Basic and Diluted					$ (0.38)	$ 0.01	$ (0.36)	$ (0.49)	$ (2.89)	$ (1.21)
Impairment of intangible assets									$ 43,836	$ 14,811
Tax benefit related to decrease in deferred tax liability for indefinite delay of further development									12,700
Income tax benefit									$ (12,656)	$ (4,282)