Segment Information (Schedule Of Operating Segment Results) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Coal Products and Services Revenue	$ 825,502	$ 1,039,651
Income (loss) from operations	(32,429)	54,081
Depreciation, depletion and amortization	118,868	139,966
Amortization of Intangible Assets	(2,810)	(14,017)
Total assets	9,920,144	10,165,118	10,006,777
Capital expenditures	54,522	93,271
PRB [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue	361,946	401,177
Income (loss) from operations	15,515	32,543
Depreciation, depletion and amortization	42,227	41,223
Amortization of Intangible Assets	(1,199)	(816)
Total assets	1,939,892	2,263,517
Capital expenditures	2,157	3,986
APP [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue	282,618	469,058
Income (loss) from operations	(27,117)	15,835
Depreciation, depletion and amortization	55,331	76,017
Amortization of Intangible Assets	(2,472)	(13,088)
Total assets	4,334,324	4,640,344
Capital expenditures	49,296	66,303
WBIT [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue	155,644	144,559
Income (loss) from operations	24,951	31,241
Depreciation, depletion and amortization	17,371	18,600
Amortization of Intangible Assets
Total assets	623,243	752,197
Capital expenditures	1,502	15,137
Other [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue	25,294	24,857
Income (loss) from operations	1,435	(3,750)
Depreciation, depletion and amortization	2,609	3,687
Amortization of Intangible Assets	861	(113)
Total assets	159,090	72,382
Capital expenditures	482	5,644
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue
Income (loss) from operations	(47,213)	(21,788)
Depreciation, depletion and amortization	1,330	439
Amortization of Intangible Assets
Total assets	2,863,595	2,436,678
Capital expenditures	$ 1,085	$ 2,201