Debt - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Disclosure [Abstract]
Interest paid on Senior Notes due 2024	$ 0	$ 3,378	$ 2,591	$ 6,756
Interest paid on Senior Notes due 2029	4,804	0	6,406	0
Interest paid on Revolving Credit Facility	450	1,204	930	1,753
Finance Lease, Interest Expense	1,018	920	1,607	1,925
Amortization of Debt Issuance Costs	487	390	891	771
Interest Expense, Other	118	181	175	216
Interest Costs Capitalized Adjustment	(1,784)	(308)	(2,597)	(528)
Interest Costs Incurred	$ 5,093	$ 5,765	$ 10,003	$ 10,893