Segment Information (Reconciliation Statement Of Segment Income from Operations To Consolidated Income Before Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting [Abstract]
Adjusted EBITDA	$ (8,360)		$ 45,328	$ (18,386)	$ 127,100
Depreciation, depletion and amortization	(58,459)		(97,372)	(122,158)	(202,246)
Amortization of acquired sales contracts, net	(1)		1,644	832	5,034
Asset impairment and mine closure costs	(43,701)	$ (85,500)	(19,146)	(129,221)	(19,146)
Interest expense, net	(44,340)		(98,612)	(87,653)	(195,491)
Nonoperating expenses	(21,271)		(4,016)	(27,359)	(4,016)
Loss before income taxes	$ (176,132)		$ (172,174)	$ (383,945)	$ (288,765)