Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lease expense
Operating lease	$ 6,872	$ 8,681
Short-term lease	4,933	5,691
Total operating lease expense	11,805	14,372
Amortization of right-of-use assets	11,327	19,171
Interest on lease liabilities	2,281	5,005
Total finance lease expense	$ 13,608	$ 24,176
Operating leases
Weighted average remaining lease term	2 years 9 months 18 days	3 years 1 month 6 days
Weighted average discount rate	12.80%	14.80%
Finance leases
Weighted average remaining lease term	2 years 2 months 12 days	2 years 1 month 6 days
Weighted average discount rate	8.30%	8.20%
Operating cash outflows from operating leases	$ 11,805	$ 14,372
Operating cash outflows from finance leases	2,281	5,005
Financing cash outflows from finance leases	$ 19,846	$ 29,364