Leases - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases
Operating lease cost	$ 12,016	$ 13,877
Finance lease cost:
Amortization of right-of-use assets	149	157
Interest on lease liabilities	48	63
Net lease cost	$ 12,213	$ 14,097
Lease expense for operating leases			$ 14,300