Income Taxes - Reconciliation of unrecognized tax benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of the beginning and ending unrecognized tax benefit
Balance at beginning of year	$ 2,163	$ 3,370	$ 3,264
Additions based on tax positions related to the current year	634	421	481
Decreases resulting from a lapse in the applicable statute of limitations	(441)	(1,628)	(375)
Balance at end of year	$ 2,356	$ 2,163	$ 3,370