Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock [Member]	Capital in Excess of Par Value	Retained Earnings (Deficit)	Accumulated Other Comprehensive Income (Loss)	Common Stock in Treasury	Total CONSOL Energy Inc. Stockholders' Equity	Non-Controlling Interest
Balance, Beginning of Period at Dec. 31, 2011	$ 3,610,885	$ 2,273	$ 2,234,775	$ 2,184,737	$ (801,554)	$ (9,346)	$ 3,610,885	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	388,073	0	0	388,470	0	0	388,470	(397)
Gas Cash Flow Hedge	75,019	0	0	0	75,019	0	75,019	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent	129,231	0	0	0	129,231	0	129,231	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	442,682	0	0	388,470	54,212	0	442,682	(397)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	442,285
Issuance of Treasury Stock	(19,641)	0	0	(28,378)	0	8,737	(19,641)	0
Proceeds from Issuance of Common Stock	8,278	11	8,267	0	0	0	8,278	0
Tax Benefit from Stock-Based Compensation	6,028	0	6,028	0	0	0	6,028	0
Amortization of Stock-Based Compensation Awards	47,838	0	47,838	0	0	0	47,838	0
Net Change in Crown Drilling Noncontrolling Interest	350	0	0	0	0	0	0	350
Dividends	142,278	0	0	142,278	0	0	142,278	0
Balance, End of Period at Dec. 31, 2012	3,953,745	2,284	2,296,908	2,402,551	(747,342)	(609)	3,953,792	(47)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	659,056	0	0	660,442	0	0	660,442	(1,386)
Gas Cash Flow Hedge	34,268	0	0	0	34,268	0	34,268	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent	456,493	0	0	0	456,493	0	456,493	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	1,082,667	0	0	660,442	422,225	0	1,082,667	(1,386)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	1,081,281
Issuance of Treasury Stock	(12,032)	0	0	(12,641)	0	609	(12,032)	0
Proceeds from Issuance of Common Stock	3,727	10	3,717	0	0	0	3,727	0
Tax Benefit from Stock-Based Compensation	(2,075)	0	(2,075)	0	0	0	(2,075)	0
Amortization of Stock-Based Compensation Awards	66,042	0	66,042	0	0	0	66,042	0
Net Change in Crown Drilling Noncontrolling Interest	1,433	0	0	0	0	0	0	1,433
Dividends	85,832	0	0	85,832	0	0	85,832	0
Balance, End of Period at Dec. 31, 2013	5,006,289	2,294	2,364,592	2,964,520	(325,117)	0	5,006,289	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	163,090	0	0	163,090	0	0	163,090	0
Gas Cash Flow Hedge	(79,028)	0	0	0	(79,028)	0	(79,028)	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent	94,989	0	0	0	94,989	0	94,989	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	337,107	0	0	163,090	174,017	0	337,107	0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	337,107
Issuance of Treasury Stock	(15,954)	0	0	(15,954)	0	0	(15,954)	0
Proceeds from Issuance of Common Stock	15,016	12	15,004	0	0	0	15,016	0
Tax Benefit from Stock-Based Compensation	2,629	0	2,629	0	0	0	2,629	0
Amortization of Stock-Based Compensation Awards	41,877	0	41,877	0	0	0	41,877	0
Dividends	57,506	0	0	57,506	0	0	57,506	0
Balance, End of Period at Dec. 31, 2014	$ 5,329,458	$ 2,306	$ 2,424,102	$ 3,054,150	$ (151,100)	$ 0	$ 5,329,458	$ 0