Leases - Lease cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Lease Cost
Amortization of leased assets	$ 6,420	$ 5,376
Interest on lease liabilities	8,177	8,868
Operating lease cost	1,079	1,305
Total lease cost	$ 15,676	$ 15,549
Weighted-average remaining lease term (in years):
Finance leases	6 years 10 months 24 days	7 years 10 months 9 days
Operating leases	8 years 3 days	7 years 3 months 7 days
Weighted-average discount rate:
Finance leases	11.05%	11.05%
Operating leases	4.73%	4.63%