Income taxes - Summary of Provision for (Benefit from) Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current:
Federal	$ 0	$ 0	$ 0
State	0	2	7
Foreign	258	684	612
Deferred:
Federal	0	0	(966)
State	0	0	(198)
Foreign	0	0	0
Total income tax expense (benefit)	$ 258	$ 686	$ (545)