Subsequent Events	12 Months Ended
Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent events	Subsequent events (a) Termination of License Agreement with Acuitas In December 2013, the Company entered into a cross-license agreement with Acuitas Therapeutics Inc., or Acuitas. The terms of the cross-license agreement provided Acuitas with access to certain of the Company's earlier intellectual property generated prior to April 2010 for a specific field. On August 29, 2016, the Company provided Acuitas with notice that it considered Acuitas to be in material breach of the cross-license agreement. The cross-license agreement provides that it may be terminated upon any material breach by the other party 60 days after receipt of written notice of termination describing the material breach in reasonable detail. On October 25, 2016, Acuitas filed a Notice of Civil Claim in the Supreme Court of British Columbia seeking an order that the Company perform its obligations under the Cross License Agreement, for damages ancillary to specific performance, injunctive relief, interest and costs. The Company disputes Acuitas’ position and have not recorded an estimate of the possible loss associated with this claim, due to the uncertainties related to both the likelihood and amount of any possible loss or range of loss. The Company has filed its response within the time frame prescribed by the Court. On February 8, 2017, the Company announced that the Supreme Court of British Columbia granted Arbutus' request for a pre-trial injunction against Acuitas, preventing Acuitas from further sublicensing of Arbutus' lipid nanoparticle (LNP) technology until the end of October 2017, or further order of the Court. Under the terms of the pre-clinical injunction, Acuitas is prevented from entering into any new agreements which include sublicensing of Arbutus' LNP. (b) LNP License with Alexion On March 16, 2017, the Company announced that it had entered into an agreement to license its LNP delivery technology to Alexion. Under the terms of the agreement, the Company will receive $7,500,000 up front and subsequent payments up to $75,000,000 for the achievement of development, regulatory and commercial milestones as well as future royalties.

Subsequent events

(a) Termination of License Agreement with Acuitas

In December 2013, the Company entered into a cross-license agreement with Acuitas Therapeutics Inc., or Acuitas. The terms of the cross-license agreement provided Acuitas with access to certain of the Company's earlier intellectual property generated prior to April 2010 for a specific field. On August 29, 2016, the Company provided Acuitas with notice that it considered Acuitas to be in material breach of the cross-license agreement. The cross-license agreement provides that it may be terminated upon any material breach by the other party 60 days after receipt of written notice of termination describing the material breach in reasonable detail. On October 25, 2016, Acuitas filed a Notice of Civil Claim in the Supreme Court of British Columbia seeking an order that the Company perform its obligations under the Cross License Agreement, for damages ancillary to specific performance, injunctive relief, interest and costs. The Company disputes Acuitas’ position and have not recorded an estimate of the possible loss associated with this claim, due to the uncertainties related to both the likelihood and amount of any possible loss or range of loss. The Company has filed its response within the time frame prescribed by the Court.

On February 8, 2017, the Company announced that the Supreme Court of British Columbia granted Arbutus' request for a pre-trial injunction against Acuitas, preventing Acuitas from further sublicensing of Arbutus' lipid nanoparticle (LNP) technology until the end of October 2017, or further order of the Court. Under the terms of the pre-clinical injunction, Acuitas is prevented from entering into any new agreements which include sublicensing of Arbutus' LNP.

(b) LNP License with Alexion

On March 16, 2017, the Company announced that it had entered into an agreement to license its LNP delivery technology to Alexion. Under the terms of the agreement, the Company will receive $7,500,000 up front and subsequent payments up to $75,000,000 for the achievement of development, regulatory and commercial milestones as well as future royalties.