Segment Information (Reconciliation Statement Of Segment Income from Operations To Consolidated Income Before Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Asset impairment and mine closure costs		$ (85,500)
Successor [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDAR	$ 120,498
Depreciation, depletion and amortization	(31,921)
Accretion on asset retirement obligations	(7,623)
Amortization of sales contracts, net	(14,690)
Asset impairment and mine closure costs	0
Interest expense, net	(8,898)
Net loss resulting from early retirement of debt and debt restructuring	(2,030)
Reorganization items, net	(2,828)
Income (loss) before income taxes	$ 52,508
Predecessor [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDAR		(1,720)
Depreciation, depletion and amortization		(63,699)
Accretion on asset retirement obligations		(8,306)
Amortization of sales contracts, net		833
Asset impairment and mine closure costs		(85,520)
Interest expense, net		(43,313)
Net loss resulting from early retirement of debt and debt restructuring		(2,213)
Reorganization items, net		(3,875)
Income (loss) before income taxes		$ (207,813)