Supplemental Guarantor Information (Summarized Balance Sheets Information) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Current assets	$ 878,737	$ 988,369
Total assets	1,830,891	1,993,230
Current liabilities	249,930	324,487
Obligor Group [Member]
Condensed Financial Statements, Captions [Line Items]
Current assets	693,625	789,562
Noncurrent assets	1,087,934	1,134,238
Total assets	1,781,559	1,923,800
Current liabilities	191,968	261,743
Noncurrent liabilities	2,044,725	2,039,138
Total liabilities	$ 2,236,693	$ 2,300,881