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Cover - shares	6 Months Ended
Cover - shares	Jun. 30, 2020	Aug. 05, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	001-34949
Entity Registrant Name	ARBUTUS BIOPHARMA CORP
Amendment Flag	false
Entity Central Index Key	0001447028
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Entity Incorporation, State or Country Code	A1
Entity Tax Identification Number	98-0597776
Entity Address, Address Line One	701 Veterans Circle
Entity Address, City or Town	Warminster
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	18974
City Area Code	267
Local Phone Number	469-0914
Title of 12(b) Security	Common Shares, without par value
Trading Symbol	ABUS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		80,909,259

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 45,899	$ 31,799
Investments in marketable securities, current	36,489	59,035
Accounts receivable	1,108	1,204
Prepaid expenses and other current assets	2,040	1,790
Total current assets	85,536	93,828
Property and equipment, net of accumulated depreciation of $6,643 (December 31, 2019: $5,642)	7,741	8,676
Investments in marketable securities, non-current	1,600	0
Right of use asset	2,575	2,738
Other non-current assets	173	293
Total assets	97,625	105,535
Current liabilities:
Accounts payable and accrued liabilities	5,813	7,235
Liability-classified options	150	253
Lease liability, current	364	340
Total current liabilities	6,327	7,828
Liability related to sale of future royalties	19,739	18,992
Contingent consideration	3,181	2,953
Lease liability, non-current	2,867	3,018
Total liabilities	32,114	32,791
Stockholders’ equity:
Preferred shares, Authorized; unlimited number without par value; Issued and outstanding: 1,164,000 (December 31, 2019: 1,164,000)	143,258	137,285
Common shares, Authorized - unlimited number with no par value, Issued and outstanding: 71,256,579 (December 31, 2019 - 64,780,314)	916,066	898,535
Additional paid-in capital	58,300	55,246
Deficit	(1,004,014)	(970,093)
Accumulated other comprehensive loss	(48,099)	(48,229)
Total stockholders’ equity	65,511	72,744
Total liabilities and stockholders’ equity	$ 97,625	$ 105,535

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Accumulated of property, plant, and equipment	$ 6,643	$ 5,642
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, shares issued (in shares)	71,256,579	64,780,314
Common shares, shares outstanding (in shares)	71,256,579	64,780,314

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue
Revenue	$ 1,514	$ 653	$ 3,005	$ 1,332
Operating expenses
Research and development	10,465	12,740	20,881	27,452
General and administrative	3,566	8,189	7,119	12,601
Depreciation and amortization	501	505	1,001	1,014
Change in fair value of contingent consideration	116	130	228	255
Site consolidation	7	(266)	64	(149)
Total operating expenses	14,655	21,298	29,293	41,173
Loss from operations	(13,141)	(20,645)	(26,288)	(39,841)
Interest income	200	606	545	1,206
Interest expense	(1,099)	(2)	(2,140)	(14)
Foreign exchange gain (loss)	(47)	60	(65)	68
Equity investment loss	0	(3,334)	0	(7,985)
Total other loss	(946)	(2,670)	(1,660)	(6,725)
Loss before income taxes	(14,087)	(23,315)	(27,948)	(46,566)
Income tax benefit	0	0	0	0
Net loss	(14,087)	(23,315)	(27,948)	(46,566)
Items applicable to preferred shares:
Dividend accretion of convertible preferred shares	(2,995)	(2,762)	(5,973)	(5,477)
Net loss attributable to common shares	$ (17,082)	$ (26,077)	$ (33,921)	$ (52,043)
Loss per share
Basic and diluted (in USD per share)	$ (0.25)	$ (0.46)	$ (0.49)	$ (0.92)
Weighted average number of common shares
Basic and diluted (in shares)	69,604,726	56,805,583	68,656,566	56,275,795
Unrealized gain on available-for-sale securities	$ 122	$ 0	$ 130	$ 0
Currency translation adjustment	0	(52)	0	(74)
Comprehensive loss	(13,965)	(23,367)	(27,818)	(46,640)
Collaborations and licenses
Revenue
Revenue	825	398	1,660	814
Non-cash royalty revenue
Revenue
Revenue	$ 689	$ 255	$ 1,345	$ 518

Condensed Consolidated Statement of Stockholders’ Equity (Unaudited) - 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, 2018		1,164,000	55,518,800
Beginning balance at Dec. 31, 2018	$ 200,234	$ 126,136	$ 879,405	$ 48,084	$ (805,221)	$ (48,170)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of accumulated dividends on Preferred Shares	0	$ (2,715)			2,715
Stock-based compensation	1,665			1,665
Certain fair value adjustments to liability stock option awards	47			47
Issuance of common shares pursuant to the Open Market Sales Agreement (in shares)			614,401
Issuance of common shares pursuant to the Open Market Sales Agreement			$ 2,248
Issuance of common shares pursuant to the Open Market Sales Agreement	2,248
Issuance of common shares pursuant to exercise of options (in shares)			122,603
Issuance of common shares pursuant to exercise of options	288		$ 490	(202)
Other comprehensive income (loss)	(22)					(22)
Net loss	(23,251)				(23,251)
Ending balance (in shares) at Mar. 31, 2019		1,164,000	56,255,804
Ending balance at Mar. 31, 2019	181,209	$ 128,851	$ 882,143	49,594	(831,187)	(48,192)
Beginning balance (in shares) at Dec. 31, 2018		1,164,000	55,518,800
Beginning balance at Dec. 31, 2018	200,234	$ 126,136	$ 879,405	48,084	(805,221)	(48,170)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(46,566)
Ending balance (in shares) at Jun. 30, 2019		1,164,000	56,850,172
Ending balance at Jun. 30, 2019	164,466	$ 131,613	$ 884,623	53,738	(857,264)	(48,244)
Beginning balance (in shares) at Mar. 31, 2019		1,164,000	56,255,804
Beginning balance at Mar. 31, 2019	181,209	$ 128,851	$ 882,143	49,594	(831,187)	(48,192)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of accumulated dividends on Preferred Shares	0	$ (2,762)			(2,762)
Stock-based compensation	3,915			3,915
Certain fair value adjustments to liability stock option awards	230			230
Issuance of common shares pursuant to the Open Market Sales Agreement (in shares)			593,689
Issuance of common shares pursuant to the Open Market Sales Agreement			$ 2,477
Issuance of common shares pursuant to the Open Market Sales Agreement	2,477
Issuance of common shares pursuant to exercise of options (in shares)			679
Issuance of common shares pursuant to exercise of options	2		$ 3	(1)
Other comprehensive income (loss)	(52)					(52)
Net loss	(23,315)				(23,315)
Ending balance (in shares) at Jun. 30, 2019		1,164,000	56,850,172
Ending balance at Jun. 30, 2019	164,466	$ 131,613	$ 884,623	53,738	(857,264)	(48,244)
Beginning balance (in shares) at Dec. 31, 2019		1,164,000	64,780,314
Beginning balance at Dec. 31, 2019	72,744	$ 137,285	$ 898,535	55,246	(970,093)	(48,229)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of accumulated dividends on Preferred Shares	0	$ 2,978			(2,978)
Stock-based compensation	1,460			1,460
Certain fair value adjustments to liability stock option awards	180			180
Issuance of common shares pursuant to the Open Market Sales Agreement (in shares)			4,147,081
Issuance of common shares pursuant to the Open Market Sales Agreement			$ 12,315
Issuance of common shares pursuant to the Open Market Sales Agreement	12,315
Issuance of common shares pursuant to exercise of options (in shares)			34,000
Issuance of common shares pursuant to exercise of options	166		$ 249	(83)
Other comprehensive income (loss)	252					252
Net loss	(13,861)				(13,861)
Ending balance (in shares) at Mar. 31, 2020		1,164,000	68,961,395
Ending balance at Mar. 31, 2020	73,256	$ 140,263	$ 911,099	56,803	(986,932)	(47,977)
Beginning balance (in shares) at Dec. 31, 2019		1,164,000	64,780,314
Beginning balance at Dec. 31, 2019	72,744	$ 137,285	$ 898,535	55,246	(970,093)	(48,229)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(27,948)
Ending balance (in shares) at Jun. 30, 2020		1,164,000	71,256,579
Ending balance at Jun. 30, 2020	65,511	$ 143,258	$ 916,066	58,300	(1,004,014)	(48,099)
Beginning balance (in shares) at Mar. 31, 2020		1,164,000	68,961,395
Beginning balance at Mar. 31, 2020	73,256	$ 140,263	$ 911,099	56,803	(986,932)	(47,977)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accretion of accumulated dividends on Preferred Shares	0	$ 2,995			(2,995)
Stock-based compensation	1,597			1,597
Certain fair value adjustments to liability stock option awards	(92)			(92)
Issuance of common shares pursuant to the Open Market Sales Agreement (in shares)			2,291,184
Issuance of common shares pursuant to the Open Market Sales Agreement			$ 5,045
Issuance of common shares pursuant to the Open Market Sales Agreement	5,045
Issuance of common shares pursuant to exercise of options (in shares)			4,000
Issuance of common shares pursuant to exercise of options	(86)		$ (78)	(8)
Other comprehensive income (loss)	(122)					(122)
Net loss	(14,087)				(14,087)
Ending balance (in shares) at Jun. 30, 2020		1,164,000	71,256,579
Ending balance at Jun. 30, 2020	$ 65,511	$ 143,258	$ 916,066	$ 58,300	$ (1,004,014)	$ (48,099)

Condensed Consolidated Statements of Cash Flow (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
OPERATING ACTIVITIES
Net loss	$ (27,948)	$ (46,566)
Non-cash items:
Depreciation	1,001	1,014
Gain on sale of property and equipment	0	(11)
Stock-based compensation expense	3,042	5,306
Unrealized foreign exchange losses (gains)	56	(95)
Change in fair value of contingent consideration	228	255
Net equity investment loss	0	7,985
Non-cash royalty revenue	(1,345)	(518)
Non-cash interest expense	2,092	0
Net accretion and amortization of investments in marketable securities	40	0
Net change in operating items:
Accounts receivable	96	(100)
Prepaid expenses and other assets	33	759
Accounts payable and accrued liabilities	(1,398)	(2,637)
Other liabilities	(151)	423
Net cash used in operating activities	(24,254)	(34,185)
INVESTING ACTIVITIES
Purchase of investments	(25,912)	(484)
Disposition of investments	46,948	71,749
Proceeds from sale of property and equipment	0	11
Acquisition of property and equipment	(66)	(271)
Net cash provided by investing activities	20,970	71,005
FINANCING ACTIVITIES
Issuance of common shares pursuant to the Open Market Sale agreement	17,360	4,725
Issuance of common shares pursuant to exercise of options	80	290
Net cash provided by financing activities	17,440	5,015
Effect of foreign exchange rate changes on cash and cash equivalents	(56)	95
Increase in cash and cash equivalents	14,100	41,930
Cash and cash equivalents, beginning of period	31,799	36,942
Cash and cash equivalents, end of period	45,899	78,872
Supplemental cash flow information
Preferred shares dividends accrued	$ (5,973)	$ (5,477)

Nature of business and future operations	6 Months Ended
Nature of business and future operations	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of business and future operations	Nature of business and future operations Arbutus Biopharma Corporation (the “Company” or “Arbutus”) is a clinical-stage biopharmaceutical company primarily focused on developing a cure for people with chronic hepatitis B virus (“HBV”) infection. The Company is advancing multiple drug product candidates that may be combined into a potentially curative regimen for chronic HBV infection. Arbutus has also initiated a drug discovery and development effort for treating coronaviruses, including COVID-19. The Company’s pipeline includes: •AB-729, a subcutaneously-delivered RNA interference (“RNAi”) product candidate currently in a Phase 1a/1b clinical trial. Preliminary positive safety data in single-dose cohorts of healthy subjects and safety and efficacy data in the 60 mg and 180 mg single-dose cohorts in subjects with chronic HBV infection were reported in March 2020. Additional follow-on week 12 data for the 60 mg single-dose cohort were reported in May 2020. The Company is dosing two 60 mg multi-dose cohorts of subjects with chronic HBV infection with dosing intervals of every four and eight weeks, respectively. The Company is also dosing subjects in a 90 mg single-dose cohort and has initiated an additional AB-729 90 mg single-dose cohort in HBV positive subjects. Results from all of these cohorts are expected in the second half of 2020. Additionally, the Company intends to initiate two 90 mg multi-dose cohorts in the second half of 2020. As the Company awaits data from the 90 mg single-dose cohorts, the Company anticipates that the dose interval for the planned 90 mg multi-dose cohorts will be every eight and twelve weeks, respectively; •AB-836, a next-generation capsid inhibitor product candidate currently advancing through IND-enabling studies, which the Company expects to be completed by the end of 2020; and •other compounds early in the development process, including oral compounds that inhibit PD-L1 and next-generation oral HBV RNA destabilizers. The Company’s research and development activities and commercialization of its products are dependent on its ability to successfully obtain adequate financing through a combination of financing activities and operations. The success of the Company is dependent on progressing its pipeline and subsequently obtaining the necessary regulatory approvals to bring its products to market and achieving profitable 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, nor to predict whether it will be successful in obtaining the necessary regulatory approvals to bring its products to market. COVID-19 In December 2019, an outbreak of a novel strain of coronavirus (COVID-19) was identified in Wuhan, China. This virus continues to spread globally, has been declared a pandemic by the World Health Organization and has spread to nearly every country in the world. The impact of this pandemic has been, and will likely continue to be, extensive in many aspects of society. The pandemic has resulted in and will likely continue to result in significant disruptions to businesses. A number of countries and other jurisdictions around the world have implemented extreme measures in an attempt to slow the spread of the virus. These measures include the closing of businesses and requiring people to stay in their homes, the latter of which raises uncertainty regarding the ability to travel to hospitals in order to participate in clinical trials. Additional measures that have had, and will likely continue to have, a major impact on clinical development, at least in the near-term, include shortages and delays in the supply chain, and prohibitions in certain countries on enrolling subjects in new clinical trials. Despite the challenges of COVID-19, we have not had to alter our objectives for 2020. However, future disruptions related to the COVID-19 pandemic could negatively impact our plans and timelines, including enrolling and monitoring subjects in our clinical trials. While Arbutus’ core mission is to find a cure for hepatitis B, the magnitude of the coronavirus pandemic is undeniable. Given the Company’s proven expertise in the discovery of new antiviral therapies, Arbutus feels compelled to work towards the discovery of a new treatment. To that end, the Company has assembled an internal team of expert scientists under the direction of Arbutus’ Chief Scientific Officer, Dr. Michael Sofia, to identify novel small molecule therapies to treat COVID-19 and future coronavirus outbreaks. Dr. Sofia, who was awarded the Lasker-DeBakey Award for his discovery of sofosbuvir, brings extensive antiviral drug discovery experience to this new program. The Company has also recently joined forces with the COVID R&D consortium to further support and expedite efforts to address the SARS-CoV-2 pandemic and any future coronavirus outbreaks. At this time, Arbutus’ COVID-19 research program will focus on the discovery and development of new molecular entities that address specific viral targets including the nsp12 viral polymerase and the viral protease. These targets are essential viral proteins which Arbutus has experience in targeting. The establishment of the COVID-19 effort does not materially impact the Company’s cash guidance for 2020 of $54 million to $58 million.

Significant accounting policies	6 Months Ended
Significant accounting policies	Jun. 30, 2020
Accounting Policies [Abstract]
Significant accounting policies	Significant accounting policies Basis of presentation These unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles for interim financial statements and accordingly, do not include all disclosures required for annual financial statements. These statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto for the year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 (the “2019 Form 10-K”). These unaudited condensed consolidated financial statements reflect, in the opinion of management, all adjustments and reclassifications necessary to fairly present the Company’s financial position as of June 30, 2020, the Company’s results of operations for the three and six months ended June 30, 2020 and the Company’s cash flows for the six months ended June 30, 2020. The results of operations for the three and six months ended June 30, 2020 are not necessarily indicative of the results for the full year. These unaudited condensed consolidated financial statements follow the same significant accounting policies as those described in the notes to the audited consolidated financial statements of the Company for the year ended December 31, 2019, except as described below under Recent Accounting Pronouncements. Principles of consolidation These unaudited condensed consolidated financial statements include the accounts of the Company and its two wholly-owned subsidiaries, Arbutus Biopharma Inc. (“Arbutus Inc.”) and Arbutus Biopharma US Holdings, Inc. All intercompany transactions and balances have been eliminated in consolidation. 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 (the “Preferred Shares”), as further described in note 11, that meet the definition of participating securities. The 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. The calculation of diluted net loss attributable to common shareholders per share does not differ from the calculation of basic net loss attributable to common shareholders per share, as the effect of the Company’s dilutive potential common shares was anti-dilutive. During the six months ended June 30, 2020 and 2019, potential common shares of 31.3 million and 27.5 million, respectively, consisting of the “if-converted” number of Preferred Shares and outstanding stock options, were excluded from the calculation of diluted net loss per common share because their inclusion would be anti-dilutive. Revenue recognition The Company recognizes revenue in accordance with ASC 606, Revenue from Contracts with Customers (”ASC 606”), which 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. Segment information The Company operates as a single segment. Recent accounting pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial position or results of operations upon adoption. In June 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments (ASC 326). The guidance is effective for the Company beginning January 1, 2023 and it changes how entities account for credit losses on financial assets and other instruments that are not measured at fair value through net income, including available-for-sale debt securities. The Company is currently evaluating the impact of the new standard on its consolidated financial statements.

Fair value of financial instruments

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Fair value of financial instruments

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 8), 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 $3.2 million as of June 30, 2020 and the increase of $0.2 million has been recorded as a component of total operating expenses in the statement of operations and comprehensive loss for the six months ended June 30, 2020. 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 table presents 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 June 30, 2020	(in thousands)
Assets
Cash and cash equivalents	$	45,899	$	—	$	—	$	45,899
Short-term investments	36,489		—		—		36,489
Long-term investments	1,600		—		—		1,600
Total	83,988		—		—		83,988
Liabilities
Liability-classified options	—		—		150		150
Contingent consideration	—		—		3,181		3,181
Total	$	—	$	—	$	3,331	$	3,331


	Level 1		Level 2		Level 3		Total
As of December 31, 2019	(in thousands)
Assets
Cash and cash equivalents	$	31,799	$	—	$	—	$	31,799
Short-term investments	59,035		—		—		59,035
Total	90,834		—		—		90,834
Liabilities
Liability-classified stock option awards	—		—		253		253
Contingent consideration	—		—		2,953		2,953
Total	$	—	$	—	$	3,206	$	3,206

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)
Six Months Ended June 30, 2020	$	253	$	—	$	(103)	$	150
Six Months Ended June 30, 2019	$	479	$	—	$	(338)	$	141

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)
Six Months Ended June 30, 2020	$	2,953	$	228	$	3,181
Six Months Ended June 30, 2019	$	3,126	$	255	$	3,381

- 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

Investments in marketable securities

6 Months Ended

Jun. 30, 2020

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 June 30, 2020	(in thousands)
Cash equivalents
Money market fund	28,606		$	—	$	—	28,606
US government agency bonds	—		—		—		—
US treasury bills	—		—		—		—
Total	$	28,606	$	—	$	—	$	28,606
Investments in marketable securities
US government agency bonds	$	15,357	$	52	$	—	$	15,409
US treasury bills	4,494		6		—		4,500
US government bonds	18,108		72		—		18,180
Total	$	37,959	$	130	$	—	$	38,089

⁽¹⁾Gross unrealized gain (loss) is pre-tax and is reported in other comprehensive loss.


	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 and is reported in other comprehensive loss.

The contractual term to maturity of the $36.5 million of short-term marketable securities held by the Company as of June 30, 2020 is less than one year. As of June 30, 2020, the Company held $1.6 million of long-term marketable securities with contractual maturities of more than one year, but less than five years. As of December 31, 2019, the Company’s $59.0 million of marketable securities had contractual maturities of less than one year. There were no realized gains or losses for the three and six months ended June 30, 2020 or 2019.

Equity method investment	6 Months Ended
Equity method investment	Jun. 30, 2020
Equity Method Investments and Joint Ventures [Abstract]
Equity method investment	Equity method investment In April 2018, Arbutus entered into an agreement with Roivant Sciences Ltd. (“Roivant”), its largest shareholder, to launch Genevant Sciences Ltd. (“Genevant”), a company focused on the discovery, development, and commercialization of a broad range of RNA-based therapeutics enabled by Arbutus’ lipid nanoparticle (“LNP”) and ligand conjugate delivery technologies. Arbutus licensed exclusive rights to its LNP and ligand conjugate delivery platforms to Genevant for RNA-based applications outside of HBV, except to the extent certain rights had already been licensed to other third parties. Arbutus retained all rights to its LNP and conjugate delivery platforms for HBV. Arbutus is entitled to receive tiered low single-digit royalties on future sales of Genevant products covered by the licensed patents. If Genevant sub-licenses the intellectual property licensed by Arbutus to Genevant, Arbutus would receive upon the commercialization of a product developed by such sub-licensee the lesser of (i) twenty percent of the revenue received by Genevant for such sublicensing and (ii) tiered low single-digit royalties on product sales by the sublicensee. As of June 30, 2020, the carrying value of Arbutus’ investment in Genevant was zero and Arbutus owned approximately 40% of the common equity of Genevant. On July 23, 2020, the United States Patent and Trademark Office before the Patent Trial and Appeal Board ("PTAB") announced their decision in Moderna Therapeutics, Inc.'s challenge of the validity of U.S. Patent 8,058,069 ("the '069 Patent"). In this decision, the PTAB determined no challenged claims were unpatentable. While Arbutus is the patent holder, this patent has been licensed to Genevant. The '069 Patent was included in this license agreement between Genevant and Arbutus. Arbutus is gratified by the recent decision of the Patent Trademark and Appeals Board, upholding the validity of one of the patents protecting its LNP technology that was licensed to Genevant. This decision reinforces Arbutus’ continuing belief in the potential of this technology. On July 31, 2020, Roivant recapitalized Genevant through an equity investment and conversion of previously issued convertible debt securities held by Roivant. Arbutus participated in the recapitalization of Genevant with an equity investment of $2.5 million. Following the recapitalization, Arbutus owns approximately 16% of the common equity of Genevant. In connection with the recapitalization, the three parties entered into an Amended and Restated Shareholders Agreement that provides Roivant with substantial control of Genevant. Arbutus has a non-voting observer seat on Genevant’s Board of Directors. Arbutus’ entitlement to receive future royalties or sublicensing revenue from Genevant was not impacted by the recapitalization.

Accounts payable and accrued liabilities

6 Months Ended

Jun. 30, 2020

Payables and Accruals [Abstract]

Accounts payable and accrued liabilities

Accounts payable and accrued liabilities are comprised of the following:


	June 30, 2020		December 31, 2019
	(in thousands)
Trade accounts payable	$	1,182	$	2,398
Research and development accruals	2,732		1,433
Professional fee accruals	304		809
Payroll accruals	1,589		2,314
Site consolidation accrual	—		137
Other accrued liabilities	6		144
Total accounts payable and accrued liabilities	$	5,813	$	7,235

Sale of future royalties

6 Months Ended

Jun. 30, 2020

Other Liabilities Disclosure [Abstract]

Sale of future royalties

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 (or “OMERS”), pursuant to which the Company sold to OMERS part of its royalty interest on future global net sales of ONPATTRO® (Patisiran) (“ONPATTRO”), an RNAi therapeutic currently being sold by Alnylam Pharmaceuticals, Inc. (“Alnylam”).

ONPATTRO utilizes Arbutus’ 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 collected by 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. 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. As of June 30, 2020, the effective annual interest rate was approximately 22%.

The Company will recognize 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 will be effectively repaid over the life of the Agreement. From the inception of the royalty sale through June 30, 2020, the Company has recorded an aggregate of $3.0 million of non-cash royalty revenue for royalties earned by OMERS. 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 three and six months ended June 30, 2020, the Company recognized non-cash royalty revenue of $0.7 million and $1.3 million, respectively, and $1.1 million and $2.1 million of related non-cash interest expense, respectively.

The table below shows the activity related to the net liability for 2020:


	Six Months Ended June 30, 2020
	(in thousands)
Net liability related to sale of future royalties - beginning balance	$	18,992
Non-cash royalty revenue	(1,345)
Non-cash interest expense	2,092
Net liability related to sale of future royalties - ending balance	$	19,739

In addition to the royalty from the 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	6 Months Ended
Contingencies and commitments	Jun. 30, 2020
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 on sales of Acrotech Biopharma LLC’s Marqibo® (formerly Spectrum Pharmaceuticals, Inc.). For the six months ended June 30, 2020 and 2019, the Company earned royalties on Marqibo sales in the amounts of $0.1 million and $0.1 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 June 30, 2020 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 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 the Company. The second phase of the 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 has accrued $0.4 million for an estimate of a potential award for costs and attorneys’ fees as of June 30, 2020. Stock Purchase Agreement with Enantigen In October 2014, Arbutus Inc., our wholly-owned subsidiary, acquired all of the outstanding shares of Enantigen Therapeutics, Inc. (“Enantigen”) pursuant to a stock purchase agreement. Through this transaction, Arbutus Inc. acquired an 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 the Company, 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 for this acquisition is a financial liability, which is measured at its fair value at each reporting period, with any changes in fair value from the previous reporting period recorded in the statements of operations and comprehensive loss (see note 3). The fair value of the contingent consideration was $3.2 million as of June 30, 2020.

Collaborations, contracts and licensing agreements

6 Months Ended

Jun. 30, 2020

Revenue from Contract with Customer [Abstract]

Collaborations, contracts and licensing agreements

Revenue contracts are described in detail in the Overview section of Part II, Item 8, “Financial Statements and Supplementary Data” in the Company’s 2019 Form 10-K.

Alnylam Pharmaceuticals, Inc. and Acuitas Therapeutics, Inc.

The Company has two royalty entitlements to Alnylam’s global net sales of ONPATTRO.

In 2012, the Company entered into a license agreement with Alnylam that entitles Alnylam to develop and commercialize certain identified 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. In July 2019, the Company sold this portion of its royalty entitlement for Alnylam’s ONPATTRO to OMERS. The Company recognizes non-cash royalty revenue for royalties on global net sales of ONPATTRO collected by OMERS. See note 7 for further details.

The Company also has rights to a second royalty interest on global net sales of ONPATTRO originating from a settlement agreement and subsequent license agreement with Acuitas Therapeutics, Inc. (“Acuitas”). This royalty entitlement from Acuitas has been retained by us and was not part of the royalty entitlement sale to OMERS.

Revenues are summarized in the following table:


	Three Months Ended June 30,						Six Months Ended June 30,
	2020		2019		2020		2019
	(in thousands)						(in thousands)
Revenue from collaborations and licenses
Acuitas Therapeutics, Inc.	$	761	$	288	$	1,514	$	645
Other milestone and royalty payments	63		110		146		169
Non-cash royalty revenue
Alnylam Pharmaceuticals, Inc.	690		255		1,345		518
Total revenue	$	1,514	$	653	$	3,005	1,332

Stockholders’ equity

6 Months Ended

Jun. 30, 2020

Stockholders' Equity Note [Abstract]

Stockholders’ equity

Open Market Sales Agreement

In December 2018, the Company entered into an Open Market Sale Agreement with Jefferies LLC (“Jefferies”) (the “Sale Agreement”), under which it could issue and sell common shares, from time to time, for an aggregate sales price of up to $50.0 million. For the three and six months ended June 30, 2019, the Company issued 593,689 and 1,208,090 common shares pursuant to the Sale Agreement resulting in net proceeds of approximately $2.5 million and $5.2 million, respectively.

In December 2019, the Company entered into an amendment to the Sale Agreement with Jefferies (the “Amended Sale Agreement”) in connection with the filing of 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 original Sale Agreement to reflect that the Company may sell its 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. During the three and six months ended June 30, 2020, the Company issued 2,291,184 and 6,438,265 common shares pursuant to the Sale Agreement and the Amended Sale Agreement, resulting in net proceeds of approximately $5.0 million and $17.4 million, respectively. During July 2020, Arbutus fully utilized the remaining availability under the Amended Sale Agreement resulting in an additional $36.5 million of net proceeds from the issuance of 9,548,780 common shares.

Stock-based compensation

The table below summarizes information about the Company’s stock based compensation for the three and six months ended June 30, 2020 and 2019 and the expense recognized in the condensed consolidated statements of operations:


	Three Months Ended June 30, 2020		Three Months Ended June 30, 2019		Six Months Ended June 30, 2020		Six Months Ended June 30, 2019
	(in thousands, except share and per share data)
Options granted during period	566,513		1,171,100		2,667,550		2,775,600
Weighted average exercise price	$	3.00	$	2.21	$	3.27	3.57

Research and development	$	681	$	817	$	1,533	1,544
General and administrative	916		2,967		1,509		3,762
Total stock compensation expense	$	1,597	$	3,784	$	3,042	5,306

Series A Preferred Shares

In October 2017, the Company entered into a subscription agreement with Roivant for the sale of 1,164,000 Preferred Shares for gross proceeds of $116.4 million. These Preferred Shares are non-voting and accrue an 8.75% per annum coupon in the form of additional Preferred Shares, compounded annually, until October 16, 2021, at which time all the Preferred Shares will be subject to mandatory conversion into common shares (subject to limited exceptions in the event of certain fundamental corporate transactions relating to Arbutus’s capital structure or assets, which would permit earlier conversion at Roivant’s option). The conversion price is $7.13 per share, which will result in the Preferred Shares being converted into approximately 23 million common shares. After conversion of the Preferred Shares into common shares, based on the number of common shares outstanding as of June 30, 2020, Roivant will hold approximately 41% of the Company’s common shares. Roivant agreed to a four year lock-up period for this investment and its existing holdings in the Company. Roivant 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 in October 2017, and the remaining amount of $66.4 million closed in January 2018 following regulatory and shareholder approvals.

The Company records the Preferred Shares wholly as equity under ASC 480, Distinguishing Liabilities From Equity, 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 preferred share capital, and an increase to deficit (see Condensed Consolidated Statement of Stockholders’ Equity).

Related Party Transactions	6 Months Ended
Related Party Transactions	Jun. 30, 2020
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Through the first quarter of 2019, the Company purchased certain research and development services from Genevant. These services were billed at agreed hourly rates and were reflective of market rates for such services. The total cost of these services during 2019 was less than $0.1 million, which was included in the Condensed Consolidated Statement of Operations under research and development. There were no such costs incurred during 2020. Conversely, Genevant purchased certain administrative and transitional services from the Company totaling $19.3 thousand and $38.5 thousand for the three and six months ended June 30, 2020, respectively. The total income from these services was $73 thousand and $189 thousand for the three and six months ended June 30, 2019, which were netted against research and development expenses in the condensed consolidated statements of operations. In addition, during 2019 Genevant had a sublease for 17,900 square feet in the Company’s Burnaby facility. Sublease income from Genevant was $62 thousand and $124 thousand for the three and six months ended June 30, 2019, and was netted against site consolidation costs and lease liability. The Company’s Burnaby facility lease and the corresponding sublease to Genevant expired on July 31, 2019.

Significant accounting policies (Policies)	6 Months Ended
Significant accounting policies (Policies)	Jun. 30, 2020
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation These unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles for interim financial statements and accordingly, do not include all disclosures required for annual financial statements. These statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto for the year ended December 31, 2019 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 (the “2019 Form 10-K”). These unaudited condensed consolidated financial statements reflect, in the opinion of management, all adjustments and reclassifications necessary to fairly present the Company’s financial position as of June 30, 2020, the Company’s results of operations for the three and six months ended June 30, 2020 and the Company’s cash flows for the six months ended June 30, 2020. The results of operations for the three and six months ended June 30, 2020 are not necessarily indicative of the results for the full year. These unaudited condensed consolidated financial statements follow the same significant accounting policies as those described in the notes to the audited consolidated financial statements of the Company for the year ended December 31, 2019, except as described below under Recent Accounting Pronouncements.
Principles of consolidation	Principles of consolidation These unaudited condensed consolidated financial statements include the accounts of the Company and its two wholly-owned subsidiaries, Arbutus Biopharma Inc. (“Arbutus Inc.”) and Arbutus Biopharma US Holdings, Inc. All intercompany transactions and balances have been eliminated in consolidation.
Net loss attributable to common shareholders per share	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 (the “Preferred Shares”), as further described in note 11, that meet the definition of participating securities. The 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. The calculation of diluted net loss attributable to common shareholders per share does not differ from the calculation of basic net loss attributable to common shareholders per share, as the effect of the Company’s dilutive potential common shares was anti-dilutive.
Revenue recognition	Revenue recognition The Company recognizes revenue in accordance with ASC 606, Revenue from Contracts with Customers (”ASC 606”), which 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.
Segment information	Segment informationThe Company operates as a single segment.
Recent accounting pronouncements	Recent accounting pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial position or results of operations upon adoption. In June 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments (ASC 326). The guidance is effective for the Company beginning January 1, 2023 and it changes how entities account for credit losses on financial assets and other instruments that are not measured at fair value through net income, including available-for-sale debt securities. The Company is currently evaluating the impact of the new standard on its consolidated financial statements.
Fair value of financial instruments	Fair value of financial instruments 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 8), 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.

- Definition

Disclosure of accounting policy for revenue from contract with customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130561-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 20
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130566-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130563-203045

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 20
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130566-203045

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 606
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-Section 50
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Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 606
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130564-203045

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130566-203045

+ Details

- Definition

Disclosure of accounting policy for segment reporting.

+ References + Details

Fair value of financial instruments (Tables)

3 Months Ended

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Assets and liabilities measured at fair value on a recurring basis


	Level 1		Level 2		Level 3		Total
As of June 30, 2020	(in thousands)
Assets
Cash and cash equivalents	$	45,899	$	—	$	—	$	45,899
Short-term investments	36,489		—		—		36,489
Long-term investments	1,600		—		—		1,600
Total	83,988		—		—		83,988
Liabilities
Liability-classified options	—		—		150		150
Contingent consideration	—		—		3,181		3,181
Total	$	—	$	—	$	3,331	$	3,331


	Level 1		Level 2		Level 3		Total
As of December 31, 2019	(in thousands)
Assets
Cash and cash equivalents	$	31,799	$	—	$	—	$	31,799
Short-term investments	59,035		—		—		59,035
Total	90,834		—		—		90,834
Liabilities
Liability-classified stock option awards	—		—		253		253
Contingent consideration	—		—		2,953		2,953
Total	$	—	$	—	$	3,206	$	3,206

Changes in fair value of liability option

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)
Six Months Ended June 30, 2020	$	253	$	—	$	(103)	$	150
Six Months Ended June 30, 2019	$	479	$	—	$	(338)	$	141

Schedule of changes in fair value of contingent consideration

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)
Six Months Ended June 30, 2020	$	2,953	$	228	$	3,181
Six Months Ended June 30, 2019	$	3,126	$	255	$	3,381

Investments in marketable securities (Tables)

6 Months Ended

Jun. 30, 2020

Investments, Debt and Equity Securities [Abstract]

Marketable securities

Investments in marketable securities consisted of the following:


	Amortized Cost		Gross Unrealized Gain⁽¹⁾		Gross Unrealized Loss⁽¹⁾		Fair Value
As of June 30, 2020	(in thousands)
Cash equivalents
Money market fund	28,606		$	—	$	—	28,606
US government agency bonds	—		—		—		—
US treasury bills	—		—		—		—
Total	$	28,606	$	—	$	—	$	28,606
Investments in marketable securities
US government agency bonds	$	15,357	$	52	$	—	$	15,409
US treasury bills	4,494		6		—		4,500
US government bonds	18,108		72		—		18,180
Total	$	37,959	$	130	$	—	$	38,089

⁽¹⁾Gross unrealized gain (loss) is pre-tax and is reported in other comprehensive loss.


	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 and is reported in other comprehensive loss.

Accounts payable and accrued liabilities (Tables)

6 Months Ended

Jun. 30, 2020

Payables and Accruals [Abstract]

Schedule of accounts payable and accrued liabilities

Accounts payable and accrued liabilities are comprised of the following:


	June 30, 2020		December 31, 2019
	(in thousands)
Trade accounts payable	$	1,182	$	2,398
Research and development accruals	2,732		1,433
Professional fee accruals	304		809
Payroll accruals	1,589		2,314
Site consolidation accrual	—		137
Other accrued liabilities	6		144
Total accounts payable and accrued liabilities	$	5,813	$	7,235

Sale of future royalties (Tables)

6 Months Ended

Jun. 30, 2020

Other Liabilities Disclosure [Abstract]

Schedule of activity related to the net liability from inception of the Agreement

The table below shows the activity related to the net liability for 2020:


	Six Months Ended June 30, 2020
	(in thousands)
Net liability related to sale of future royalties - beginning balance	$	18,992
Non-cash royalty revenue	(1,345)
Non-cash interest expense	2,092
Net liability related to sale of future royalties - ending balance	$	19,739

Collaborations, contracts and licensing agreements (Tables)

6 Months Ended

Jun. 30, 2020

Revenue from Contract with Customer [Abstract]

Schedule of revenue recognized under collaborations, contracts and licensing agreements

Revenues are summarized in the following table:


	Three Months Ended June 30,						Six Months Ended June 30,
	2020		2019		2020		2019
	(in thousands)						(in thousands)
Revenue from collaborations and licenses
Acuitas Therapeutics, Inc.	$	761	$	288	$	1,514	$	645
Other milestone and royalty payments	63		110		146		169
Non-cash royalty revenue
Alnylam Pharmaceuticals, Inc.	690		255		1,345		518
Total revenue	$	1,514	$	653	$	3,005	1,332

Stockholders’ equity (Tables)

6 Months Ended

Jun. 30, 2020

Stockholders' Equity Note [Abstract]

Schedule of stock based compensation expense


	Three Months Ended June 30, 2020		Three Months Ended June 30, 2019		Six Months Ended June 30, 2020		Six Months Ended June 30, 2019
	(in thousands, except share and per share data)
Options granted during period	566,513		1,171,100		2,667,550		2,775,600
Weighted average exercise price	$	3.00	$	2.21	$	3.27	3.57

Research and development	$	681	$	817	$	1,533	1,544
General and administrative	916		2,967		1,509		3,762
Total stock compensation expense	$	1,597	$	3,784	$	3,042	5,306

Significant accounting policies (Details) shares in Millions	6 Months Ended
	Jun. 30, 2020 subsidiary shares	Jun. 30, 2019 shares
Accounting Policies [Abstract]
Wholly-owed subsidiaries \| subsidiary	2
Anti-dilutive common shares excluded from calculation of loss per common share (in shares) \| shares	31.3	27.5

Fair value of financial instruments - Narrative (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair value of contingent consideration	$ 3,181	$ 3,381	$ 2,953	$ 3,126
Increase (decrease) in fair value of contingent consideration	$ 228	$ 255

Fair value of financial instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Assets
Long-term investments	$ 1,600	$ 0
Liabilities
Contingent consideration	3,181	2,953	$ 3,381	$ 3,126
Recurring
Assets
Cash and cash equivalents	45,899	31,799
Short-term investments	36,489	59,035
Long-term investments	1,600
Total	83,988	90,834
Liabilities
Liability-classified options	150	253
Contingent consideration	3,181	2,953
Total	3,331	3,206
Recurring \| Level 1
Assets
Cash and cash equivalents	45,899	31,799
Short-term investments	36,489	59,035
Long-term investments	1,600
Total	83,988	90,834
Liabilities
Liability-classified options	0	0
Contingent consideration	0	0
Total	0	0
Recurring \| Level 2
Assets
Cash and cash equivalents	0	0
Short-term investments	0	0
Long-term investments	0
Total	0	0
Liabilities
Liability-classified options	0	0
Contingent consideration	0	0
Total	0	0
Recurring \| Level 3
Assets
Cash and cash equivalents	0	0
Short-term investments	0	0
Long-term investments	0
Total	0	0
Liabilities
Liability-classified options	150	253
Contingent consideration	3,181	2,953
Total	$ 3,331	$ 3,206

Fair value of financial instruments - Changes in Fair Value of Liabilities-Classified as Stock Option (Details) - Liability classified stock options - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Fair Value, Liabilities Measured on Recurring Basis [Roll Forward]
Liability at beginning of the period	$ 253	$ 479
Fair value of liability-classified options exercised in the period	0	0
Increase (decrease) in fair value of liability	(103)	(338)
Liability at end of the period	$ 150	$ 141

Fair value of financial instruments - Changes in Fair Value of Contingent Consideration (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Fair Value, Liabilities Measured on Recurring Basis [Roll Forward]
Liability at beginning of the period	$ 2,953	$ 3,126
Increase (decrease) in fair value of liability	228	255
Liability at end of the period	$ 3,181	$ 3,381

Investments in marketable securities- Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 36,500	$ 59,000
Cash equivalents
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	28,606	7,116
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	28,606	7,116
Cash equivalents \| Money market fund
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	28,606	4,106
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	28,606	4,106
Cash equivalents \| US government agency bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	0	1,511
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	0	1,511
Cash equivalents \| US treasury bills
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	0	1,499
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	0	1,499
Investments in marketable securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	37,959	59,035
Gross Unrealized Gain	130	4
Gross Unrealized Loss	0	(4)
Fair Value	38,089	59,035
Investments in marketable securities \| US government agency bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	15,357	19,863
Gross Unrealized Gain	52	2
Gross Unrealized Loss	0	(1)
Fair Value	15,409	19,864
Investments in marketable securities \| US treasury bills
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,494	15,926
Gross Unrealized Gain	6	2
Gross Unrealized Loss	0	(1)
Fair Value	4,500	15,927
Investments in marketable securities \| US government bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	18,108	23,246
Gross Unrealized Gain	72	0
Gross Unrealized Loss	0	(2)
Fair Value	$ 18,180	$ 23,244

Investments in marketable securities - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Marketable Securities [Line Items]
Investments in marketable securities, current	$ 36,500,000		$ 36,500,000		$ 59,000,000.0
Investments in marketable securities, non-current	1,600,000		1,600,000		0
Investments in marketable securities
Marketable Securities [Line Items]
Investments in marketable securities, current	38,089,000		38,089,000		$ 59,035,000
Realized gains or losses	$ 0	$ 0	$ 0	$ 0

Equity method investment (Details) - Genevant - USD ($)	Jul. 31, 2020	Jun. 30, 2020
Schedule of Equity Method Investments [Line Items]
Equity investment		$ 0
Ownership interest in equity method investment		40.00%
Subsequent Event
Schedule of Equity Method Investments [Line Items]
Equity investment	$ 2,500,000
Ownership interest in equity method investment	16.00%

Accounts payable and accrued liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Trade accounts payable	$ 1,182	$ 2,398
Research and development accruals	2,732	1,433
Professional fee accruals	304	809
Payroll accruals	1,589	2,314
Site consolidation accrual	0	137
Other accrued liabilities	6	144
Accounts payable and accrued liabilities	$ 5,813	$ 7,235

Sale of future royalties - Narrative (Details) - USD ($)			3 Months Ended	6 Months Ended		12 Months Ended
	Jul. 02, 2019	Jan. 01, 2019	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020
Other Liabilities Disclosure [Line Items]
Royalty guarantees commitments percentage				2.50%
Non-cash royalty revenue				$ 1,345,000	$ 518,000
Non-cash interest expense			$ 1,100,000	$ 2,092,000
OMERS
Other Liabilities Disclosure [Line Items]
Annual royalty revenue	$ 500,000,000
Gross proceeds from sale of royalty interest. before advisory fees		$ 20,000,000
Entitlement of royalties to be received	$ 30,000,000
Royalty guarantees commitments percentage	100.00%
Future royalty payments	$ 30,000,000
Transaction costs on sale of royalties	$ 1,500,000
Effective annual interest rate on royalty liability				22.00%
Non-cash royalty revenue			$ (700,000)	$ (1,300,000)		$ (3,000,000.0)
OMERS \| Minimum
Other Liabilities Disclosure [Line Items]
Royalty interest sold percentage	1.00%
OMERS \| Maximum
Other Liabilities Disclosure [Line Items]
Royalty interest sold percentage	2.33%

Sale of future royalties - Liability Activity (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Liability Related To Sale Of Future Royalties [Roll Forward]
Net liability related to sale of future royalties - beginning balance		$ 18,992
Non-cash royalty revenue		(1,345)
Non-cash interest expense	$ 1,100	2,092
Net liability related to sale of future royalties - ending balance	$ 19,739	$ 19,739

Contingencies and commitments (Details) $ in Millions			1 Months Ended	6 Months Ended			53 Months Ended
Contingencies and commitments (Details) $ in Millions	Aug. 20, 2019 USD ($)	Jan. 16, 2015 USD ($)	Jun. 30, 2017 USD ($) Legal_proceedings	Jun. 30, 2020 USD ($)	Jun. 30, 2020 CAD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2004 USD ($)	Mar. 31, 2004 CAD ($)	Jun. 30, 2020 CAD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Oct. 31, 2014 USD ($) product
Contingencies and Commitments [Line Items]
Percent of costs funded by TPC							27.00%	27.00%
Maximum contribution for product							$ 7,200,000	$ 9.3
Cumulative contribution for product				$ 2,700,000	$ 3.7
Royalty guarantees commitments percentage				2.50%	2.50%
Estimate of potential arbitration award for costs and attorney's fees				$ 400,000
Fair value of contingent consideration				3,181,000		$ 3,381,000				$ 2,953,000	$ 3,126,000
Recurring
Contingencies and Commitments [Line Items]
Fair value of contingent consideration				3,181,000						2,953,000
Enantigen \| Recurring \| Blumberg and Drexel
Contingencies and Commitments [Line Items]
Fair value of contingent consideration				3,200,000						$ 0
Arbutus Inc. \| Blumberg and Drexel
Contingencies and Commitments [Line Items]
Development and regulatory milestones payment per licensed compound series, maximum												$ 102,500,000
Development and regulatory milestones payment per royalty, maximum												1,000,000.0
Arbutus Inc. \| Enantigen
Contingencies and Commitments [Line Items]
Business combination, high end of payment upon achievement of certain triggering events												$ 21,000,000.0
Number of products covered by patent acquired under the agreement \| product												2
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
Number of legal proceedings \| Legal_proceedings			3
Arbitration settlement, amount awarded to other party	$ 5,900,000
Arbitration settlement interest	2,600,000
Arbitration settlement payment	$ 5,900,000
Royalty
Contingencies and Commitments [Line Items]
Royalties paid or accrued				100,000
Contractual obligation				2,700,000					$ 3.7
Royalty \| Acrotech Biopharma
Contingencies and Commitments [Line Items]
Royalties earned				$ 100,000		$ 100,000

Collaborations, contracts and licensing agreements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue	$ 1,514	$ 653	$ 3,005	$ 1,332
Revenue from collaborations and licenses \| Acuitas Therapeutics, Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue	761	288	1,514	645
Revenue from collaborations and licenses \| Other milestone and royalty payments
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue	63	110	146	169
Non-cash royalty revenue
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue	689	255	1,345	518
Non-cash royalty revenue \| Alnylam Pharmaceuticals, Inc.
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue	$ 690	$ 255	$ 1,345	$ 518

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
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-Section S99
-Paragraph 1
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Subparagraph (SX 210.9-05(b)(2))
-URI http://asc.fasb.org/extlink&oid=120399901&loc=d3e537907-122884

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

+ Details

Stockholders’ equity - Additional Information (Details) - USD ($)	1 Months Ended			3 Months Ended				6 Months Ended
	Jul. 31, 2020	Jan. 31, 2018	Oct. 31, 2017	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Proceeds from issuance of shares under the agreement								$ 17,360,000	$ 4,725,000
Issuance of common shares pursuant to the agreement				$ 5,045,000	$ 12,315,000	$ 2,477,000	$ 2,248,000
Preferred Shares
Class of Stock [Line Items]
Shares issued (in shares)			1,164,000
Roivant Sciences Ltd
Class of Stock [Line Items]
Ownership percentage by noncontrolling owners after conversion				41.00%				41.00%
Maximum ownership percentage by noncontrolling owners			49.99%
Proceeds from sale of stock		$ 66,400,000	$ 50,000,000.0
Roivant Sciences Ltd \| Convertible Preferred Stock
Class of Stock [Line Items]
Issuance of common shares pursuant to the agreement			$ 116,400,000
Preferred stock dividend rate as a percent			8.75%	8.75%
Preferred stated value (in dollars per share)			$ 7.13
Number of common shares to be issued upon conversion of convertible preferred stock			23,000,000
Investment commitment period			4 years
Open Market Sale Agreement \| Jefferies LLC \| Common Shares
Class of Stock [Line Items]
Aggregate sale price of common shares under agreement										$ 50,000,000.0	$ 50,000,000.0
Number of shares issued under agreement (in sales)				2,291,184		593,689		6,438,265	1,208,090
Proceeds from issuance of shares under the agreement				$ 5,000,000.0		$ 2,500,000		$ 17,400,000	$ 5,200,000
Open Market Sale Agreement \| Jefferies LLC \| Common Shares \| Subsequent Event
Class of Stock [Line Items]
Number of shares issued under agreement (in sales)	9,548,780
Proceeds from issuance of shares under the agreement	$ 36,500,000

Stockholders’ equity - Stock-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 1,597	$ 3,784	$ 3,042	$ 5,306
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	916	2,967	1,509	3,762
Research and Development Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 681	$ 817	$ 1,533	$ 1,544
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price (in USD per share)	$ 3.00	$ 2.21	$ 3.27	$ 3.57
Arbutus Plans \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted during period (in shares)	566,513	1,171,100	2,667,550	2,775,600

Related Party Transactions (Details) - Genevant - Equity Method Investee	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) ft²
Research and development services
Related Party Transaction [Line Items]
Expenses from transactions with related party			$ 0		$ 100,000
Administrative and transitional services
Related Party Transaction [Line Items]
Expenses from transactions with related party	$ 19,300		$ 38,500
Income from related party		$ 73,000		$ 189,000
Sublease, Burnaby facility
Related Party Transaction [Line Items]
Sublease income		$ 62,000		$ 124,000
Area of sublease facility \| ft²					17,900