Long-Term Debt - Credit Facility Net Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revolving Credit Facility | Line of Credit
Interest Expense and Amortization of Debt Issue Costs
Interest expense	$ 2,339	$ 603	$ 3,969	$ 715
Debt issue cost amortization	275	141	461	283
Unused facility fee	32	149	141	329
Total	2,646	893	4,571	1,327
6.125% Senior Notes | Senior Notes
Interest Expense and Amortization of Debt Issue Costs
Interest expense	8,697	8,680	17,390	17,357
Debt issue cost amortization	321	321	642	640
Debt discount amortization	275	258	546	513
Total	$ 9,293	$ 9,259	$ 18,578	$ 18,510