Supplemental Quarterly Info (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Impairment of Oil and Gas Properties									$ 0	$ 828,905	$ 0
Sales	$ 390,398	$ 688,590	$ 602,772	$ 235,251	$ 478,864	$ 631,979	$ 503,825	$ 715,740	2,026,375	2,693,339	3,204,023
Freight-Outside	12,519	9,392	10,295	11,447	13,110	2,436	2,750	5,018	46,468	20,499	23,133
Cost of Goods Sold and Other Operating Charges (exclusive of depreciation, depletion and amortization shown below)	415,224	361,551	243,267	369,392	329,071	267,826	351,200	399,281
Freight Expense	12,519	9,392	10,295	11,447	13,110	2,436	2,750	5,018	46,468	20,499	23,133
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax	19,564	(34,975)	(11,017)	(234,605)	(53,167)	(3,842)	(25,417)	26,067	(303,183)	(14,209)	(1,857)
Income (Loss) from Continuing Operations Attributable to Parent	(321,198)	62,568	45,342	(234,044)	(43,291)	129,312	(577,884)	52,964	(544,919)	(360,676)	164,947
Net Income Attributable to CONSOL Energy Inc Shareholders	$ (306,047)	$ 25,345	$ 30,405	$ (469,828)	$ (97,572)	$ 118,980	$ (603,301)	$ 79,031	$ (848,102)	$ (374,885)	$ 163,090
Basic	$ (1.33)	$ 0.11	$ 0.13	$ (2.05)	$ (0.43)	$ 0.52	$ (2.64)	$ 0.34	$ (3.70)	$ (1.64)	$ 0.71
Income (Loss) from Continuing Operations, Per Diluted Share	(1.42)	0.26	0.18	(1.03)	(0.19)	0.54	(2.52)	0.23	(2.38)	(1.57)	0.71
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0.09	(0.15)	(0.05)	(1.02)	(0.24)	(0.02)	(0.12)	0.11	(1.32)	(0.07)	(0.01)
Income (Loss) from Continuing Operations, Per Basic Share	(1.42)	0.26	0.18	(1.03)	(0.19)	0.54	(2.52)	0.23	(2.38)	(1.57)	0.72
Diluted	(1.33)	0.11	0.13	(2.05)	(0.43)	0.52	(2.64)	0.34	(3.70)	(1.64)	0.70
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	$ 0.09	$ (0.15)	$ (0.05)	$ (1.02)	$ (0.24)	$ (0.02)	$ (0.12)	$ 0.11	$ (1.32)	$ (0.07)	$ (0.01)