Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	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, 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
Amortization of Stock-Based Compensation Awards	41,877	0	41,877	0	0	0	41,877	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	174,017
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	2,629	0	2,629	0	0	0	2,629	0
Net Income (Loss)	(364,475)	0	0	(374,885)	0	0	(374,885)	10,410
Gas Cash Flow Hedge	78,051	0	0	0	78,051	0	78,051	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent	(86,447)	0	0	0	(86,447)	0	(86,447)	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	(539,383)	0	0	(374,885)	(164,498)	0	(539,383)	10,410
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(528,973)
Issuance of Treasury Stock	(12,181)	0	0	(12,181)	0	0	(12,181)	0
Proceeds from Issuance of Common Stock	8,288	10	8,278	0	0	0	8,288	0
Stock Repurchased During Period, Value	(71,674)	(22)	(17,683)	(53,969)	0	0	(71,674)	0
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(3,706)	0	(3,706)	0	0	0	(3,706)	0
Amortization of Stock-Based Compensation Awards	24,506	0	24,506	0	0	0	24,506	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(5,060)	0	0	0	0	0	0	(5,060)
Net Change in Noncontrolling Interest	148,399	0	0	0	0	0	0	148,399
Dividends	33,281	0	0	33,281	0	0	33,281	0
Balance, End of Period at Dec. 31, 2015	4,855,776	2,294	2,435,497	2,579,834	(315,598)	0	4,702,027	153,749
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	(164,498)
Net Income (Loss)	(839,148)
Gas Cash Flow Hedge	43,470	0	0	0	43,470	0	43,470	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent	(33,226)	0	0	0	(33,488)	0	(33,488)	(262)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	(925,060)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(915,844)	0	0	(848,102)	(76,958)	0	(925,060)	9,216
Stock Granted, Value, Share-based Compensation, Forfeited	(1,649)	0	0	(1,649)	0	0	(1,649)	0
Proceeds from Issuance of Common Stock	4	4	0	0	0	0	4	0
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(4,931)	0	(4,931)	0	0	0	(4,931)	0
Amortization of Stock-Based Compensation Awards	31,483	0	30,298	0	0	0	30,298	1,185
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(21,657)
Net Change in Noncontrolling Interest	(21,657)	0	0	0	0	0	0	(21,657)
Dividends	2,294	0	0	(2,294)	0	0	(2,294)	0
Balance, End of Period at Dec. 31, 2016	3,940,888	$ 2,298	$ 2,460,864	$ 1,727,789	$ (392,556)	$ 0	$ 3,798,395	$ 142,493
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	$ (76,696)