Supplemental Quarterly Info (Unaudited) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Sales	$ 1,383,431	$ 1,439,930	$ 1,503,435	$ 1,405,293	$ 1,307,769	$ 1,282,154	$ 1,236,007	$ 1,186,869
Freight-Outside	75,225	59,871	59,572	36,868	29,171	37,269	28,075	31,200	231,536	125,715	148,907
Cost of Goods Sold and Other Operating Charges (exclusive of depreciation, depletion and amortization shown below)	894,543	895,075	943,541	831,192	842,273	870,560	831,638	781,367	3,501,189	3,262,327	2,757,052
Freight Expense	75,225	59,871	59,572	36,679	29,000	37,269	28,075	31,200	231,347	125,544	148,907
Net Income (Loss)	195,635	167,329	77,384	192,149	104,461	75,383	70,900	107,882	632,497	358,626	567,142
Net Income Attributable to CONSOL Energy Inc Shareholders	$ 195,635	$ 167,329	$ 77,384	$ 192,149	$ 104,461	$ 75,383	$ 66,668	$ 100,269	$ 632,497	$ 346,781	$ 539,717
Basic	$ 0.86	$ 0.74	$ 0.34	$ 0.85	$ 0.46	$ 0.33	$ 0.30	$ 0.55	$ 2.79	$ 1.61	$ 2.99
Diluted	$ 0.85	$ 0.73	$ 0.34	$ 0.84	$ 0.46	$ 0.33	$ 0.29	$ 0.54	$ 2.76	$ 1.60	$ 2.95
Weighted Average Number of Shares Outstanding, Basic	226,971,597	226,744,011	226,647,752	226,350,594	225,854,413	225,781,539	225,715,539	181,726,480	226,680,369	214,920,561	180,693,243
Diluted	229,314,370	229,163,537	229,138,024	228,814,838	228,169,569	228,092,299	228,081,103	184,348,982	229,003,599	217,037,804	182,821,136