Leases - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating lease cost
Operating lease expense	$ 1,196	$ 1,180	$ 3,555	$ 3,529
Variable lease expense	1,016	1,066	2,883	2,669
Finance lease cost
Amortization of right-of-use assets	90	88	267	236
Interest on lease liabilities	255	245	748	722
Total lease expense	2,557	2,579	7,453	7,156
Other information
Operating cash flows outflows related to operating leases	1,424	1,440	5,855	5,412
Operating cash flows outflows related to financing leases	151	151	678	616
Financing cash flows outflows related to financing leases	6	143	162	3,310
Right-of-use assets obtained in exchange for new finance lease liabilities	1,420	0	1,420	7,212
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 8,298	$ 0	$ 8,298	$ 0
Weighted-average remaining lease term (excluding renewal options) - operating leases	47 years 9 months 18 days	48 years 10 months 24 days	47 years 9 months 18 days	48 years 10 months 24 days
Weighted-average remaining lease term (excluding renewal options) - finance leases	63 years 2 months 12 days	64 years 8 months 12 days	63 years 2 months 12 days	64 years 8 months 12 days
Weighted-average discount rate - operating leases	5.60%	5.70%	5.60%	5.70%
Weighted-average discount rate - finance leases	5.40%	5.40%	5.40%	5.40%