Significant Accounting Policy Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent	$ 146,595	$ (72,169)	$ 107,580	$ 8,562	$ (3,725)	$ (26,316)	$ 155,789	$ 80,906	$ 79,264	$ 317,959	$ 681,675
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax	591,144	8,120	42,060	(21,375)	1,904	14,814	(3,050)	16,290	579,792	70,114	(49,178)
Less: Net Loss (Income) Attributable to Noncontrolling Interest									1,386	397	0
Net Income Attributable to CONSOL Energy Inc Shareholders	$ 738,183	$ (63,651)	$ 149,903	$ (12,526)	$ (1,564)	$ (11,368)	$ 152,739	$ 97,196	$ 660,442	$ 388,470	$ 632,497
Weighted Average Number of Shares Outstanding, Basic									228,728,628	227,593,524	226,680,369
Effect of stock-based compensation awards									1,349,314	1,548,243	2,323,230
Weighted Average Number of Shares Outstanding, Diluted									230,077,942	229,141,767	229,003,599
Earnings Per Share, Basic	$ 3.22	$ (0.28)	$ 0.66	$ (0.05)	$ (0.01)	$ (0.05)	$ 0.67	$ 0.43	$ 2.89	$ 1.71	$ 2.79
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	$ 2.58	$ 0.03	$ 0.19	$ (0.09)	$ 0.01	$ 0.07	$ (0.01)	$ 0.07	$ 2.54	$ 0.31	$ (0.22)
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.64	$ (0.31)	$ 0.47	$ 0.04	$ (0.02)	$ (0.12)	$ 0.68	$ 0.36	$ 0.35	$ 1.40	$ 3.01
Earnings Per Share, Diluted	$ 3.20	$ (0.28)	$ 0.65	$ (0.05)	$ (0.01)	$ (0.05)	$ 0.67	$ 0.42	$ 2.87	$ 1.70	$ 2.76
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	$ 2.56	$ 0.03	$ 0.18	$ (0.09)	$ 0.01	$ 0.07	$ (0.01)	$ 0.07	$ 2.52	$ 0.31	$ (0.22)
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.64	$ (0.31)	$ 0.47	$ 0.04	$ (0.02)	$ (0.12)	$ 0.68	$ 0.35	$ 0.35	$ 1.39	$ 2.98