Nature of Business, Interim Financial Data and Basis of Presentation (Condensed Supplemental Cash Flow) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Supplemental disclosures of cash flow information:
Interest paid			$ 30,435	$ 41,978
Income taxes (refunded) paid			(202)	14,134
Supplemental disclosures of non-cash flow information:
Revenue	$ 146,022	$ 279,673	373,936	547,169
Reconciliation of cash and cash equivalents and restricted cash to the Condensed Consolidated Balance Sheet:
Cash and cash equivalents	196,914	20,500	196,914	20,500	$ 15,142
Restricted cash	0	2,466	0	2,466	1,865
Total cash and cash equivalents and restricted cash	196,914	22,966	196,914	22,966	$ 17,007	$ 30,038
Trade
Supplemental disclosures of non-cash flow information:
Revenue	5,800	10,700	14,921	23,980
Expense	$ 6,100	$ 11,400	$ 14,172	$ 22,008