Guarantor Subsidiaries Income Statement (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Oil and Gas Sales Revenue									$ 1,028,117,000	$ 737,701,000	$ 658,820,000
Coal Products and Services Revenue									2,052,166,000	2,018,067,000	2,169,625,000
Other Revenue, Net									276,242,000	259,783,000	294,105,000
Gas Royalty Interests and Purchased Gas Sales									91,427,000	69,733,000	52,721,000
Freight-Outside	5,597,000	2,497,000	3,946,000	10,109,000	9,945,000	9,579,000	9,660,000	12,253,000	28,148,000	35,438,000	107,079,000
Other Income									207,103,000	111,483,000	113,170,000
Gain (Loss) on Disposition of Assets									43,601,000	67,480,000	282,006,000
Total Revenue and Other Income									3,726,804,000	3,299,685,000	3,677,526,000
Oil and Gas Property, Lease Operating Expense									118,391,000	96,601,000	90,837,000
Gas Gathering, Transportation, Marketing and Processing Costs									258,110,000	201,024,000	160,579,000
Production Tax Expense									39,418,000	28,676,000	26,145,000
E&P Direct Administration and Selling									55,092,000	49,092,000	47,565,000
E&P Depreciation, Depletion, and Amortization									314,381,000	231,809,000	205,149,000
Exploration and Production Costs									23,356,000	61,104,000	39,005,000
Production Royalty Interests and Purchased Gas Costs									77,185,000	57,865,000	41,578,000
Income (Loss) from Continuing Operations before Income Taxes, Domestic									183,124,000	46,075,000	406,687,000
Other Expenses									86,499,000	95,535,000	81,033,000
Results of Operations, General and Administrative Related to Oil and Gas Producing Activities									64,047,000	39,047,000	33,686,000
Oil and Gas Production Expense									1,036,479,000	860,753,000	725,577,000
Operating Expenses									1,349,832,000	1,345,797,000	1,457,913,000
Taxes, Miscellaneous									100,890,000	102,128,000	117,194,000
Direct Administration, Selling and Other Costs									44,185,000	49,018,000	54,910,000
Coal Depreciation, Depletion, Amortization									254,914,000	226,639,000	219,636,000
Freight Expense	5,597,000	2,497,000	3,946,000	10,109,000	9,945,000	9,579,000	9,660,000	12,253,000	28,148,000	35,438,000	107,079,000
General and Administrative Expense									45,160,000	40,047,000	42,662,000
Other Cost and Expense, Operating									55,321,000	55,802,000	52,900,000
Cost of Coal Products and Services									1,878,450,000	1,854,869,000	2,052,294,000
Other Nonoperating Expense									307,236,000	315,180,000	269,653,000
Other General and Administrative Expense									788,000	936,000	943,000
Depreciation, Depletion and Amortization, Nonproduction									1,896,000	2,674,000	2,330,000
Gains (Losses) on Extinguishment of Debt									95,267,000	0	0
Interest Expense									223,564,000	219,198,000	220,042,000
Other General Expense									628,751,000	537,988,000	492,968,000
Total Costs									3,543,680,000	3,253,610,000	3,270,839,000
Income Taxes									14,347,000	(33,189,000)	88,728,000
Income (Loss) from Continuing Operations Attributable to Parent	73,666,000	(1,645,000)	146,595,000	(24,935,000)	121,691,000	(72,169,000)	8,562,000	(3,724,000)	168,777,000	79,264,000	317,959,000
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									(5,687,000)	579,792,000	70,114,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									163,090,000	659,056,000	388,073,000
Net Income (Loss) Attributable to Noncontrolling Interest									0	(1,386,000)	(397,000)
Net Income Attributable to CONSOL Energy Inc Shareholders	73,666,000	(1,645,000)	738,183,000	(24,935,000)	116,004,000	(63,651,000)	(12,526,000)	(1,564,000)	163,090,000	660,442,000	388,470,000
Parent Issuer
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Oil and Gas Sales Revenue									0	0	0
Coal Products and Services Revenue									0	0	0
Other Revenue, Net									0	0	0
Gas Royalty Interests and Purchased Gas Sales									0	0	0
Freight-Outside									0	0	0
Other Income									458,322,000	930,481,000	613,340,000
Gain (Loss) on Disposition of Assets									0	0	0
Total Revenue and Other Income									458,322,000	930,481,000	613,340,000
Oil and Gas Property, Lease Operating Expense									0	0	0
Gas Gathering, Transportation, Marketing and Processing Costs									0	0	0
Production Tax Expense									0	0	0
E&P Direct Administration and Selling									0	0	0
E&P Depreciation, Depletion, and Amortization									0	0	0
Exploration and Production Costs									0	0	0
Production Royalty Interests and Purchased Gas Costs									0	0	0
Income (Loss) from Continuing Operations before Income Taxes, Domestic									(12,622,000)	496,126,000	251,636,000
Other Expenses									0	0	0
Results of Operations, General and Administrative Related to Oil and Gas Producing Activities									0	0	0
Oil and Gas Production Expense									0	0	0
Operating Expenses									23,524,000	14,743,000	9,292,000
Taxes, Miscellaneous									0	0	0
Direct Administration, Selling and Other Costs									0	0	0
Coal Depreciation, Depletion, Amortization									558,000	12,160,000	11,491,000
Freight Expense									0	0	0
General and Administrative Expense									0	0	0
Other Cost and Expense, Operating									55,321,000	55,802,000	52,900,000
Cost of Coal Products and Services									79,403,000	82,705,000	73,683,000
Other Nonoperating Expense									76,124,000	139,927,000	78,861,000
Other General and Administrative Expense									0	0	0
Depreciation, Depletion and Amortization, Nonproduction									82,000	697,000	266,000
Gains (Losses) on Extinguishment of Debt									95,267,000
Interest Expense									220,068,000	211,026,000	208,894,000
Other General Expense									391,541,000	351,650,000	288,021,000
Total Costs									470,944,000	434,355,000	361,704,000
Income Taxes									(175,712,000)	(164,316,000)	(136,834,000)
Income (Loss) from Continuing Operations Attributable to Parent									163,090,000	660,442,000	388,470,000
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									0	0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									163,090,000	660,442,000	388,470,000
Net Income (Loss) Attributable to Noncontrolling Interest										0	0
Net Income Attributable to CONSOL Energy Inc Shareholders									163,090,000	660,442,000	388,470,000
Cnx Gas Guarantor [Member]
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Oil and Gas Sales Revenue									1,030,574,000	741,090,000	661,192,000
Coal Products and Services Revenue									0	0	0
Other Revenue, Net									0	0	0
Gas Royalty Interests and Purchased Gas Sales									91,427,000	69,733,000	52,721,000
Freight-Outside									0	0	0
Other Income									67,308,000	36,371,000	45,232,000
Gain (Loss) on Disposition of Assets									45,917,000	21,000,000	10,964,000
Total Revenue and Other Income									1,235,226,000	868,194,000	770,109,000
Oil and Gas Property, Lease Operating Expense									118,391,000	96,601,000	90,837,000
Gas Gathering, Transportation, Marketing and Processing Costs									258,110,000	201,024,000	160,579,000
Production Tax Expense									39,418,000	28,676,000	26,145,000
E&P Direct Administration and Selling									55,092,000	49,092,000	47,565,000
E&P Depreciation, Depletion, and Amortization									314,381,000	231,809,000	205,149,000
Exploration and Production Costs									23,356,000	61,104,000	39,005,000
Production Royalty Interests and Purchased Gas Costs									77,197,000	57,906,000	41,633,000
Income (Loss) from Continuing Operations before Income Taxes, Domestic									189,714,000	(1,204,000)	39,384,000
Other Expenses									86,499,000	95,534,000	81,028,000
Results of Operations, General and Administrative Related to Oil and Gas Producing Activities									64,047,000	39,047,000	33,686,000
Oil and Gas Production Expense									1,036,491,000	860,793,000	725,627,000
Operating Expenses									0	0	0
Taxes, Miscellaneous									0	0	0
Direct Administration, Selling and Other Costs									0	0	0
Coal Depreciation, Depletion, Amortization									0	0	0
Freight Expense									0	0	0
General and Administrative Expense									0	0	0
Other Cost and Expense, Operating									0	0	0
Cost of Coal Products and Services									0	0	0
Other Nonoperating Expense									0	0	0
Other General and Administrative Expense									0	0	0
Depreciation, Depletion and Amortization, Nonproduction									0	0	0
Gains (Losses) on Extinguishment of Debt									0
Interest Expense									9,021,000	8,605,000	5,098,000
Other General Expense									9,021,000	8,605,000	5,098,000
Total Costs									1,045,512,000	869,398,000	730,725,000
Income Taxes									66,441,000	1,420,000	15,021,000
Income (Loss) from Continuing Operations Attributable to Parent									123,273,000	(2,624,000)	24,363,000
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									0	0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									123,273,000	(2,624,000)	24,363,000
Net Income (Loss) Attributable to Noncontrolling Interest										(1,386,000)	(397,000)
Net Income Attributable to CONSOL Energy Inc Shareholders									123,273,000	(1,238,000)	24,760,000
Other Subsidiary Guarantors
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Oil and Gas Sales Revenue									0	0	0
Coal Products and Services Revenue									2,052,166,000	2,018,067,000	2,169,625,000
Other Revenue, Net									41,255,000	43,364,000	51,046,000
Gas Royalty Interests and Purchased Gas Sales									0	0	0
Freight-Outside									28,148,000	35,438,000	107,079,000
Other Income									130,072,000	54,612,000	46,313,000
Gain (Loss) on Disposition of Assets									(2,337,000)	46,366,000	271,029,000
Total Revenue and Other Income									2,249,304,000	2,197,847,000	2,645,092,000
Oil and Gas Property, Lease Operating Expense									0	0	0
Gas Gathering, Transportation, Marketing and Processing Costs									0	0	0
Production Tax Expense									0	0	0
E&P Direct Administration and Selling									0	0	0
E&P Depreciation, Depletion, and Amortization									0	0	0
Exploration and Production Costs									0	0	0
Production Royalty Interests and Purchased Gas Costs									0	0	0
Income (Loss) from Continuing Operations before Income Taxes, Domestic									447,799,000	582,099,000	752,057,000
Other Expenses									0	0	0
Results of Operations, General and Administrative Related to Oil and Gas Producing Activities									0	0	0
Oil and Gas Production Expense									0	0	0
Operating Expenses									1,328,766,000	1,174,638,000	1,356,575,000
Taxes, Miscellaneous									100,890,000	102,128,000	117,194,000
Direct Administration, Selling and Other Costs									44,185,000	49,018,000	54,910,000
Coal Depreciation, Depletion, Amortization									254,356,000	214,479,000	208,145,000
Freight Expense									28,148,000	35,438,000	107,079,000
General and Administrative Expense									45,160,000	40,047,000	42,662,000
Other Cost and Expense, Operating									0	0	0
Cost of Coal Products and Services									1,801,505,000	1,615,748,000	1,886,565,000
Other Nonoperating Expense									0	0	0
Other General and Administrative Expense									0	0	0
Depreciation, Depletion and Amortization, Nonproduction									0	0	0
Gains (Losses) on Extinguishment of Debt									0
Interest Expense									0	0	6,470,000
Other General Expense									0	0	6,470,000
Total Costs									1,801,505,000	1,615,748,000	1,893,035,000
Income Taxes									119,559,000	126,164,000	204,105,000
Income (Loss) from Continuing Operations Attributable to Parent									328,240,000	455,935,000	547,952,000
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									0	0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									328,240,000	455,935,000	547,952,000
Net Income (Loss) Attributable to Noncontrolling Interest										0	0
Net Income Attributable to CONSOL Energy Inc Shareholders									328,240,000	455,935,000	547,952,000
Non-Guarantors
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Oil and Gas Sales Revenue									0	0	0
Coal Products and Services Revenue									0	0	0
Other Revenue, Net									234,987,000	216,419,000	243,059,000
Gas Royalty Interests and Purchased Gas Sales									0	0	0
Freight-Outside									0	0	0
Other Income									9,668,000	20,500,000	21,626,000
Gain (Loss) on Disposition of Assets									21,000	114,000	13,000
Total Revenue and Other Income									244,676,000	237,033,000	264,698,000
Oil and Gas Property, Lease Operating Expense									0	0	0
Gas Gathering, Transportation, Marketing and Processing Costs									0	0	0
Production Tax Expense									0	0	0
E&P Direct Administration and Selling									0	0	0
E&P Depreciation, Depletion, and Amortization									0	0	0
Exploration and Production Costs									0	0	0
Production Royalty Interests and Purchased Gas Costs									0	0	0
Income (Loss) from Continuing Operations before Income Taxes, Domestic									10,727,000	9,367,000	17,012,000
Other Expenses									0	0	0
Results of Operations, General and Administrative Related to Oil and Gas Producing Activities									0	0	0
Oil and Gas Production Expense									0	0	0
Operating Expenses									0	0	0
Taxes, Miscellaneous									0	0	0
Direct Administration, Selling and Other Costs									0	0	0
Coal Depreciation, Depletion, Amortization									0	0	0
Freight Expense									0	0	0
General and Administrative Expense									0	0	0
Other Cost and Expense, Operating									0	0	0
Cost of Coal Products and Services									0	0	0
Other Nonoperating Expense									231,112,000	224,706,000	244,635,000
Other General and Administrative Expense									788,000	936,000	943,000
Depreciation, Depletion and Amortization, Nonproduction									1,814,000	1,977,000	2,064,000
Gains (Losses) on Extinguishment of Debt									0
Interest Expense									235,000	47,000	44,000
Other General Expense									233,949,000	227,666,000	247,686,000
Total Costs									233,949,000	227,666,000	247,686,000
Income Taxes									4,059,000	3,543,000	6,436,000
Income (Loss) from Continuing Operations Attributable to Parent									6,668,000	5,824,000	10,576,000
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									(5,687,000)	579,792,000	70,114,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									981,000	585,616,000	80,690,000
Net Income (Loss) Attributable to Noncontrolling Interest										0	0
Net Income Attributable to CONSOL Energy Inc Shareholders									981,000	585,616,000	80,690,000
Elimination
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Oil and Gas Sales Revenue									(2,457,000)	(3,389,000)	(2,372,000)
Coal Products and Services Revenue									0	0	0
Other Revenue, Net									0	0	0
Gas Royalty Interests and Purchased Gas Sales									0	0	0
Freight-Outside									0	0	0
Other Income									(458,267,000)	(930,481,000)	(613,341,000)
Gain (Loss) on Disposition of Assets									0	0	0
Total Revenue and Other Income									(460,724,000)	(933,870,000)	(615,713,000)
Oil and Gas Property, Lease Operating Expense									0	0	0
Gas Gathering, Transportation, Marketing and Processing Costs									0	0	0
Production Tax Expense									0	0	0
E&P Direct Administration and Selling									0	0	0
E&P Depreciation, Depletion, and Amortization									0	0	0
Exploration and Production Costs									0	0	0
Production Royalty Interests and Purchased Gas Costs									(12,000)	(41,000)	(55,000)
Income (Loss) from Continuing Operations before Income Taxes, Domestic									(452,494,000)	(1,040,313,000)	(653,402,000)
Other Expenses									0	1,000	5,000
Results of Operations, General and Administrative Related to Oil and Gas Producing Activities									0	0	0
Oil and Gas Production Expense									(12,000)	(40,000)	(50,000)
Operating Expenses									(2,458,000)	156,416,000	92,046,000
Taxes, Miscellaneous									0	0	0
Direct Administration, Selling and Other Costs									0	0	0
Coal Depreciation, Depletion, Amortization									0	0	0
Freight Expense									0	0	0
General and Administrative Expense									0	0	0
Other Cost and Expense, Operating									0	0	0
Cost of Coal Products and Services									(2,458,000)	156,416,000	92,046,000
Other Nonoperating Expense									0	(49,453,000)	(53,843,000)
Other General and Administrative Expense									0	0	0
Depreciation, Depletion and Amortization, Nonproduction									0	0	0
Gains (Losses) on Extinguishment of Debt									0
Interest Expense									(5,760,000)	(480,000)	(464,000)
Other General Expense									(5,760,000)	(49,933,000)	(54,307,000)
Total Costs									(8,230,000)	106,443,000	37,689,000
Income Taxes									0	0	0
Income (Loss) from Continuing Operations Attributable to Parent									(452,494,000)	(1,040,313,000)	(653,402,000)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent									0	0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									(452,494,000)	(1,040,313,000)	(653,402,000)
Net Income (Loss) Attributable to Noncontrolling Interest										0	0
Net Income Attributable to CONSOL Energy Inc Shareholders									$ (452,494,000)	$ (1,040,313,000)	$ (653,402,000)