Segment Information (Schedule Of Operating Segment Results) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Coal Products and Services Revenue	$ 968,231	$ 1,087,618	$ 1,063,538	$ 1,039,651	$ 1,228,756	$ 1,198,673	$ 985,528	$ 872,938	$ 4,159,038	$ 4,285,895	$ 3,186,268
Income (loss) from operations	(282,645)	135,960	(588,984)	54,081	139,728	76,256	95,354	102,238	(681,588)	413,576	323,984
Depreciation, depletion and amortization									525,508	466,587	365,066
Amortization of acquired sales contacts, net									(25,189)	(22,069)	35,606
Goodwill and other intangible asset impairment									346,423
Total assets	10,006,777				10,213,959				10,006,777	10,213,959	4,880,769
Capital expenditures									395,225	540,936	314,657
PRB [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue									1,524,537	1,646,947	1,606,236
Income (loss) from operations									100,679	180,730	146,555
Depreciation, depletion and amortization									166,539	171,693	185,218
Amortization of acquired sales contacts, net									(1,987)	19,458	35,606
Total assets	1,972,522				2,307,783				1,972,522	2,307,783	2,295,786
Capital expenditures									23,410	110,999	38,142
APP [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue									1,793,575	1,915,090	1,042,490
Income (loss) from operations									148,512	283,404	193,943
Depreciation, depletion and amortization									271,220	203,759	97,764
Amortization of acquired sales contacts, net									(23,925)	(39,988)	0
Total assets	3,875,105				4,740,723				3,875,105	4,740,723	706,624
Capital expenditures									275,476	217,435	70,839
WBIT [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue									728,089	672,766	537,542
Income (loss) from operations									144,421	119,665	58,082
Depreciation, depletion and amortization									71,696	81,235	80,497
Amortization of acquired sales contacts, net											0
Total assets	658,255				681,393				658,255	681,393	677,611
Capital expenditures									58,465	66,356	65,470
Other [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue									112,837	51,092	0
Income (loss) from operations									5,145	(4,685)	0
Depreciation, depletion and amortization									11,512	7,876	0
Amortization of acquired sales contacts, net									723	(1,539)	0
Total assets	176,032				581,040				176,032	581,040	0
Capital expenditures									9,928	28,243	0
Corporate, Other and Eliminations [Member]
Segment Reporting Information [Line Items]
Coal Products and Services Revenue											0
Income (loss) from operations									(1,080,345)	(165,538)	(74,596)
Depreciation, depletion and amortization									4,541	2,024	1,587
Amortization of acquired sales contacts, net											0
Total assets	3,324,863				1,903,020				3,324,863	1,903,020	1,200,748
Capital expenditures									$ 27,946	$ 117,903	$ 140,206