Stockholders' Equity - Reclassifications From Accumulated Other Comprehensive Loss (Details) - 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
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax	$ 0		$ 0		$ 0
Predecessor
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax		$ 1,436		$ 1,008
Prior service cost
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	0		0		0
Prior service cost | Predecessor
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax		(33)		(133)
Actuarial loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	0		0		0
Actuarial loss | Predecessor
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax		1,326		998
Defined Benefit Pension and Postretirement Items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	0		0		0
Tax effect	0		0		0
Total reclassifications for the period, net of tax	$ 0		$ 0		$ 0
Defined Benefit Pension and Postretirement Items | Predecessor
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax		1,293		865
Tax effect		143		143
Total reclassifications for the period, net of tax		$ 1,436		$ 1,008