Leases - Components of Lease Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Finance lease cost:
Amortization of assets	$ 1,015	$ 1,039	$ 2,028	$ 2,077
Interest on lease liabilities	468	482	937	971
Operating lease expense:
Operating lease cost	2,265	2,239	4,497	4,502
Variable lease cost	286	268	556	532
Sublease income	(49)	(47)	(98)	(95)
Total lease costs	$ 3,985	$ 3,981	$ 7,920	$ 7,987