Fair Value Measurements - Carrying Value and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Nov. 20, 2018	Nov. 19, 2018
Fair Value Disclosure
Long-term debt				$ 1,035,641
Receivable from unconsolidated subsidiaries		$ 204,790	$ 204,790
Carrying Value
Fair Value Disclosure
Cash and cash equivalents	$ 278,620	367,577
Carrying Value | First Lien Notes
Fair Value Disclosure
Long-term debt	747,910	747,400
Carrying Value | Second Lien PIK Notes
Fair Value Disclosure
Long-term debt	325,824	291,935
Estimated Fair Value
Fair Value Disclosure
Cash and cash equivalents	278,620	367,577
Estimated Fair Value | Fair Value, Inputs, Level 2 | First Lien Notes
Fair Value Disclosure
Long-term debt	682,500	714,953
Estimated Fair Value | Fair Value, Inputs, Level 2 | Second Lien PIK Notes
Fair Value Disclosure
Long-term debt	$ 183,949	$ 285,548