Contingencies and Commitments (Details) $ in Thousands			1 Months Ended	3 Months Ended			53 Months Ended
	Aug. 20, 2019 USD ($)	Jan. 16, 2015 USD ($)	Jun. 30, 2017 USD ($) Legal_proceedings	Mar. 31, 2020 USD ($)	Mar. 31, 2020 CAD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2004 USD ($)	Mar. 31, 2004 CAD ($)	Mar. 31, 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	$ 9,300
Cumulative contribution for product				$ 2,700,000	$ 3,700
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				3,065,000		$ 3,251,000				$ 2,953,000	$ 3,126,000
Arbutus Inc. | Enantigen
Contingencies and Commitments [Line Items]
Business combination, high end of payment upon achievement of certain triggering events												$ 21,000,000
Number of products covered by patent acquired under the agreement | product												2
Blumberg and Drexel | Arbutus Inc.
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
Recurring
Contingencies and Commitments [Line Items]
Fair value of contingent consideration				3,065,000						2,953,000
Recurring | Blumberg and Drexel | Enantigen
Contingencies and Commitments [Line Items]
Fair value of contingent consideration				3,100,000						$ 0
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
Royalties
Contingencies and Commitments [Line Items]
Minimum annual royalty revenue				82,500		$ 41,361
Royalties paid or accrued				100,000
Contractual obligation				$ 2,679,000					$ 3,700