Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Allowance for slow-moving and obsolete inventories	$ 0	$ 6,000
Successor [Member]
Property, Plant and Equipment [Line Items]
Coal	37,268
Repair parts and supplies	76,194
Inventories	$ 113,462
Predecessor [Member]
Property, Plant and Equipment [Line Items]
Coal		85,043
Repair parts and supplies		111,677
Inventories		$ 196,720