Lease liabilities - Additional Information (Detail)					12 Months Ended
	Dec. 23, 2019 USD ($) ft²	Sep. 23, 2019 ft²	Dec. 22, 2016 ft²	Nov. 01, 2016 ft²	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Finance lease liability annual payment							$ 66,000
Deferred rent liability					$ 313,000
Operating lease costs					$ 700,000	$ 700,000
Finance lease liability aggregate purchase price of Asset							300,000
Operating Lease Right Of Use Asset							770,000
Finance Lease Right Of Use Asset							$ 300,000
Percentage of Increase In Lease Rent							2.50%
Canada [Member]
Lessee, Lease, Description [Line Items]
Square feet of office space leased | ft²			2,500	10,946
Lease agreement, commencement date			Dec. 22, 2016	Nov. 01, 2016
Lease agreement, expiration date			Jun. 30, 2019	Oct. 31, 2021
Lease agreement extended period				Oct. 31, 2026
USA [Member]
Lessee, Lease, Description [Line Items]
Square feet of office space leased | ft²	33,300	6,272
Lease agreement, commencement date	Dec. 01, 2020	Oct. 01, 2019
Finance lease liability annual payment	$ 2.0
Lease agreement, expiration date	Dec. 01, 2028	Oct. 31, 2021