Voluntary Reorganization under Chapter 11 - Liabilities Subject to Compromise (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Reorganizations [Abstract]
Senior notes due 2023	$ 700,000	$ 0
Accrued interest	7,331
Accounts payable	181,068
Accrued prepetition facility closing and restructuring costs	7,077
Accrued postretirement obligations other than pensions	31,791
Other accrued expenses	100,126
Liabilities subject to compromise	$ 1,027,393	$ 0