Income taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of beginning of period	$ 4,403	$ 3,070
Increases (decreases) for tax positions related to current period	36	1,333
Increases (decreases) for tax positions related to prior periods		0
Increases (decreases) for tax positions as part of separation adjustment	(4,403)
Balance as of end of period	$ 36	$ 4,403