Inventories - Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Allowance for excess and obsolete inventories:
Balance, beginning of period	$ 3,261	$ 2,644	$ 1,210
Provisions for excess and obsolete inventories	629	1,108	1,454
Inventories written off	(2,103)	(491)	(20)
Balance, end of period	$ 1,787	$ 3,261	$ 2,644