Consolidated income tax provision (benefit) (Details) - USD ($) $ in Thousands	4 Months Ended	8 Months Ended	12 Months Ended
	Apr. 22, 2016	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2015
Predecessor [Member]
Summary of consolidated income tax provision (benefit)
Current income taxes	$ 0			$ (410)
Deferred income taxes	0			(80,133)
Income tax provision (benefit)	$ 0			$ (80,543)
Successor [Member]
Summary of consolidated income tax provision (benefit)
Current income taxes		$ 0	$ (1,954)
Deferred income taxes		0	0
Income tax provision (benefit)		$ 0	$ (1,954)