Lease liabilities - Additional Information (Detail) $ in Thousands				3 Months Ended
	Dec. 23, 2019 USD ($) ft² Option	Sep. 23, 2019 ft²	Nov. 01, 2016 ft²	Mar. 31, 2020 USD ($) Payment	Jan. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Tenant Improvements	$ 8,000
Additional tenant improvements	$ 1,500
Cash deposit				$ 500
Finance lease liability aggregate purchase price of Asset				$ 300
Lease agreement, expiration month year				2023-06
Number of annual payments | Payment				5
Operating lease right-of-use assets				$ 10,300		$ 770
Finance lease right-of-use assets				$ 300		$ 300
Irrevocable Letters of Credit [Member]
Lessee, Lease, Description [Line Items]
Cash deposit					$ 500
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
Lease agreement, expiration date	Dec. 01, 2028	Oct. 31, 2021
Number of option to extend lease | Option	2
Lease agreement option to extend lease term	5 years
Canada [Member]
Lessee, Lease, Description [Line Items]
Square feet of office space leased | ft²			10,946
Lease agreement, commencement date			Nov. 01, 2016
Lease agreement, expiration date			Oct. 31, 2021
Lease agreement extended period			Oct. 31, 2026