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	Dec. 31, 2020
Lease Cost
Amortization of leased assets	$ 1,693	$ 1,344	$ 4,726	$ 4,032
Interest on lease liabilities	2,045	2,217	6,133	6,651
Operating lease cost:	270	286	809	1,081
Total leased cost	$ 4,008	$ 3,847	$ 11,668	$ 11,764
Weighted-average remaining lease term (in years)
Finance leases	7 years 1 month 17 days		7 years 1 month 17 days		7 years 10 months 9 days
Operating leases	8 years 3 days		8 years 3 days		7 years 3 months 7 days
Weighted-average discount rate:
Finance leases	11.05%		11.05%		11.05%
Operating leases	4.76%		4.76%		4.63%