Workers' Compensation Expense (Worker's Compensation Expense) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Successor [Member] | Workers' Compensation [Member]
Accrued Workers' Compensation [Line Items]
Total workers’ compensation expense	$ 5,605
Successor [Member] | Occupational Disease [Member]
Accrued Workers' Compensation [Line Items]
Service cost	1,558
Interest cost	1,169
Net amortization	0
Total occupational disease	2,727
Successor [Member] | Traumatic Injury Claims and Assessments [Member]
Accrued Workers' Compensation [Line Items]
Traumatic injury claims and assessments	$ 2,878
Predecessor [Member] | Workers' Compensation [Member]
Accrued Workers' Compensation [Line Items]
Total workers’ compensation expense		$ 6,270
Predecessor [Member] | Occupational Disease [Member]
Accrued Workers' Compensation [Line Items]
Service cost		1,105
Interest cost		1,057
Net amortization		1,141
Total occupational disease		3,303
Predecessor [Member] | Traumatic Injury Claims and Assessments [Member]
Accrued Workers' Compensation [Line Items]
Traumatic injury claims and assessments		$ 2,967