Segment Information (Schedule Of Operating Segment Results) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]
Revenues	$ 735,971	$ 737,370
Income (loss) from operations	(73,122)	(51,431)
Depreciation, depletion and amortization	104,423	110,193
Depreciation, depletion and amortization	104,423	118,868
Amortization of acquired sales contracts, net	(3,696)	(2,810)
Capital expenditures	14,454	54,522
PRB [Member]
Segment Reporting Information [Line Items]
Revenues	358,607	361,946
Income (loss) from operations	(4,898)	15,516
Depreciation, depletion and amortization	39,245	42,227
Amortization of acquired sales contracts, net	(789)	(1,199)
Capital expenditures	2,094	2,157
APP [Member]
Segment Reporting Information [Line Items]
Revenues	279,137	282,618
Income (loss) from operations	(25,728)	(27,116)
Depreciation, depletion and amortization	54,988	55,331
Amortization of acquired sales contracts, net	(2,974)	(2,472)
Capital expenditures	8,156	49,297
Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues	98,227	92,806
Income (loss) from operations	1,635	7,384
Depreciation, depletion and amortization	9,519	11,304
Amortization of acquired sales contracts, net	67	861
Capital expenditures	1,801	763
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues
Income (loss) from operations	(44,131)	(47,215)
Depreciation, depletion and amortization	671	1,331
Amortization of acquired sales contracts, net	0	0
Capital expenditures	$ 2,403	$ 2,305