Workers' Compensation Expense (Schedule of Amounts Recognized in Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015
Accrued Workers' Compensation [Line Items]
Total obligations	$ 203,617	$ 199,752
Less amount included in accrued expenses	18,782	15,184
Noncurrent obligations	184,835	184,568
Occupational disease costs
Accrued Workers' Compensation [Line Items]
Occupational disease costs	122,426	111,159
Occupational disease costs | Successor
Accrued Workers' Compensation [Line Items]
Occupational disease costs	122,426	111,159	$ 119,710
Occupational disease costs | Predecessor
Accrued Workers' Compensation [Line Items]
Occupational disease costs			$ 119,710	$ 90,836
Traumatic and other workers’ compensation claims
Accrued Workers' Compensation [Line Items]
Occupational disease costs	$ 81,191	$ 88,593