Workers' Compensation Expense (Worker's Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015	Dec. 31, 2014
Successor [Member]
Accrued Workers' Compensation [Line Items]
Service cost	$ 1,583
Interest cost	1,126
Net amortization	0
Successor [Member] | Workers' Compensation [Member]
Accrued Workers' Compensation [Line Items]
Total workers’ compensation expense	5,871
Successor [Member] | Occupational Disease [Member]
Accrued Workers' Compensation [Line Items]
Service cost	1,583
Interest cost	1,126
Total occupational disease	2,709
Successor [Member] | Traumatic Injury Claims and Assessments [Member]
Accrued Workers' Compensation [Line Items]
Traumatic injury claims and assessments	$ 3,162
Predecessor [Member]
Accrued Workers' Compensation [Line Items]
Service cost		$ 3,465	$ 4,282	$ 1,734
Interest cost		3,184	3,944	2,914
Net amortization		4,325	6,973	(216)
Predecessor [Member] | Workers' Compensation [Member]
Accrued Workers' Compensation [Line Items]
Total workers’ compensation expense		17,602	31,980	24,356
Predecessor [Member] | Occupational Disease [Member]
Accrued Workers' Compensation [Line Items]
Service cost		3,465	4,282
Interest cost		3,184	3,944
Total occupational disease		10,974	15,199	4,432
Predecessor [Member] | Traumatic Injury Claims and Assessments [Member]
Accrued Workers' Compensation [Line Items]
Traumatic injury claims and assessments		$ 6,628	$ 16,781	$ 19,924