Employee Benefit Plans - Schedule of Net Benefit Costs (Details) - Pension and Other Postretirement Plans, Defined Benefit - USD ($) $ in Thousands	1 Months Ended	2 Months Ended	3 Months Ended	8 Months Ended	9 Months Ended
	Sep. 30, 2017	Aug. 31, 2017	Sep. 30, 2018	Aug. 31, 2017	Sep. 30, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 38		$ 117		$ 351
Interest cost	397		1,225		3,675
Expected return on assets	(692)		(1,971)		(5,913)
Amortization of prior service cost	0		0		0
Amortization of actuarial loss	0		0		0
Net periodic pension and postretirement benefit credit	(257)		(629)		(1,887)
Contributions paid	$ 213		$ 0		$ 0
Predecessor
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost		$ 71		$ 282
Interest cost		806		3,227
Expected return on assets		(1,356)		(5,425)
Amortization of prior service cost		33		133
Amortization of actuarial loss		110		438
Net periodic pension and postretirement benefit credit		(336)		(1,345)
Contributions paid		$ 0		$ 356