CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	4 Months Ended	8 Months Ended	12 Months Ended
	Dec. 31, 2016	Sep. 12, 2016	Dec. 31, 2018	Dec. 31, 2017
Successor [Member]
Net income (loss)	$ (5,296)		$ 224,785	$ 32,662
Other comprehensive income (loss):
Change in pension and postretirement obligations, net of tax of $0 for 2018 and 2017, $39 for the Successor period from September 13, 2016 through December 31, 2016 and $(226) for the Predecessor period from January 1, 2016 through September 12, 2016.	73		82	(73)
Total other comprehensive income (loss), net of tax	73		82	(73)
Comprehensive income (loss)	$ (5,223)		$ 224,867	$ 32,589
Predecessor [Member]
Net income (loss)		$ 1,054,602
Other comprehensive income (loss):
Change in pension and postretirement obligations, net of tax of $0 for 2018 and 2017, $39 for the Successor period from September 13, 2016 through December 31, 2016 and $(226) for the Predecessor period from January 1, 2016 through September 12, 2016.		(421)
Total other comprehensive income (loss), net of tax		(421)
Comprehensive income (loss)		$ 1,054,181