Leases - Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 2,572	$ 2,704	$ 8,182	$ 8,085
Finance lease cost:
Amortization of right-of-use assets	390	688	1,505	1,998
Interest on lease liabilities	62	164	258	532
Short-term lease cost	3,138	5,420	10,054	10,642
Variable lease cost	33	30	83	80
Total lease cost	$ 6,195	$ 9,006	$ 20,082	$ 21,337