Guarantor Subsidiaries Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current Assets:
Cash and Cash Equivalents	$ 60,475	$ 72,574	$ 176,985	$ 327,420
Accounts and Notes Receivable:
Trade	220,222	151,383
Inventories	65,461	66,792
Income Taxes Receivable, Current	116,851	13,887
Prepaid Expenses	93,146	297,287
Other Receivables, Net, Current	69,901	121,735
Disposal Group, Including Discontinued Operation, Assets, Current	83	81,105
Total Current Assets	626,139	804,763
Property, Plant and Equipment:
Property, Plant and Equipment, Gross	13,771,388	13,794,907
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	5,630,949	5,062,201
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment	0	936,671
Total Property, Plant and Equipment-Net	8,140,439	9,669,377
Other Assets:
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	190,964	237,330
Other	222,149	214,388
Disposal Group, Including Discontinued Operation, Other Assets	0	4,044
Total Assets	9,183,981	10,929,902	$ 11,654,646
Other Assets	417,403	455,762
Current Liabilities:
Other Accrued Liabilities, Current	680,348	421,827
Disposal Group, Including Discontinued Operation, Liabilities, Current	6,050	51,514
Accounts Payable	241,616	250,609
Accounts Payable (Recoverable)- Related Parties	0	0
Total Current Liabilities	940,014	1,685,359
Short-Term Notes Payable (Note 12)	0	952,000
Long-term Debt, Excluding Current Maturities	2,722,995	2,703,899
Long-term Debt and Capital Lease Obligations, Including Current Maturities		2,738,783
Disposal Group, Including Discontinued Operation, Liabilities	0	5,001
Long-term Debt and Capital Lease Obligations	2,762,069	2,743,784
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent	0	74,629
Postretirement Benefits Other Than Pensions	659,474	630,892
Pneumoconiosis	108,073	111,903
Mine Closing	218,631	227,339
Gas Well Closing	223,352	163,842
Workers' Compensation	67,277	69,812
Salary Retirement	112,543	91,596
Reclamation	0	25
Other	151,660	166,957
Noncontrolling Interest in Limited Partnerships	142,493	153,749
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent	0	107,988
Total deferred credits and other liabilities	1,541,010	1,644,983
Long-term Debt and Capital Lease Obligations, Current	12,000	9,409
Total CONSOL Energy Inc. Stockholders' Equity	3,798,395	4,702,027
TOTAL LIABILITIES AND EQUITY	9,183,981	10,929,902
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	4,290	0
Parent Company [Member]
Current Assets:
Cash and Cash Equivalents	49,722	64,995
Accounts and Notes Receivable:
Trade	0	0
Inventories	0	0
Income Taxes Receivable, Current	175,877	72,913
Prepaid Expenses	12,828	27,245
Other Receivables, Net, Current	20,097	18,933
Disposal Group, Including Discontinued Operation, Assets, Current	0	0
Total Current Assets	258,524	184,086
Property, Plant and Equipment:
Property, Plant and Equipment, Gross	114,611	156,348
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	84,788	111,367
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment		0
Total Property, Plant and Equipment-Net	29,823	44,981
Other Assets:
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	7,974,260	10,563,985
Other	19,960	53,529
Disposal Group, Including Discontinued Operation, Other Assets		0
Total Assets	8,308,471	10,846,581
Other Assets	8,020,124	10,617,514
Current Liabilities:
Other Accrued Liabilities, Current	75,039	63,668
Disposal Group, Including Discontinued Operation, Liabilities, Current	0	0
Accounts Payable	48,666	32,245
Accounts Payable (Recoverable)- Related Parties	1,832,908	2,650,732
Total Current Liabilities	1,958,146	3,700,154
Short-Term Notes Payable (Note 12)		952,000
Long-term Debt and Capital Lease Obligations, Including Current Maturities		2,418,961
Disposal Group, Including Discontinued Operation, Liabilities		0
Long-term Debt and Capital Lease Obligations	2,421,511	2,418,961
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent		(122,547)
Postretirement Benefits Other Than Pensions	0	0
Pneumoconiosis	0	0
Mine Closing	0	0
Gas Well Closing	0	0
Workers' Compensation	0	0
Salary Retirement	112,543	91,596
Reclamation		0
Other	17,876	56,390
Noncontrolling Interest in Limited Partnerships	0	0
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		0
Total deferred credits and other liabilities	130,419	25,439
Long-term Debt and Capital Lease Obligations, Current	1,533	1,509
Total CONSOL Energy Inc. Stockholders' Equity	3,798,395	4,702,027
TOTAL LIABILITIES AND EQUITY	8,308,471	10,846,581
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	25,904
Cnx Gas Guarantor [Member]
Current Assets:
Cash and Cash Equivalents	83	75
Accounts and Notes Receivable:
Trade	124,509	72,664
Inventories	15,301	13,815
Income Taxes Receivable, Current	(59,026)	(59,026)
Prepaid Expenses	60,500	244,680
Other Receivables, Net, Current	34,773	99,001
Disposal Group, Including Discontinued Operation, Assets, Current	0	0
Total Current Assets	176,140	371,209
Property, Plant and Equipment:
Property, Plant and Equipment, Gross	8,851,226	8,875,027
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	3,106,296	2,695,674
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment		0
Total Property, Plant and Equipment-Net	5,744,930	6,179,353
Other Assets:
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	188,376	234,803
Other	67,096	47,892
Disposal Group, Including Discontinued Operation, Other Assets		0
Total Assets	6,154,928	6,833,257
Other Assets	233,858	282,695
Current Liabilities:
Other Accrued Liabilities, Current	337,374	102,753
Disposal Group, Including Discontinued Operation, Liabilities, Current	0	0
Accounts Payable	127,309	149,930
Accounts Payable (Recoverable)- Related Parties	1,034,138	1,521,442
Total Current Liabilities	1,505,190	1,780,923
Short-Term Notes Payable (Note 12)		0
Long-term Debt and Capital Lease Obligations, Including Current Maturities		33,141
Disposal Group, Including Discontinued Operation, Liabilities		0
Long-term Debt and Capital Lease Obligations	26,884	33,141
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent		197,176
Postretirement Benefits Other Than Pensions	0	0
Pneumoconiosis	0	0
Mine Closing	0	0
Gas Well Closing	195,704	135,174
Workers' Compensation	0	0
Salary Retirement	0	0
Reclamation		0
Other	117,658	105,588
Noncontrolling Interest in Limited Partnerships	0	0
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		0
Total deferred credits and other liabilities	313,362	437,938
Long-term Debt and Capital Lease Obligations, Current	6,369	6,798
Total CONSOL Energy Inc. Stockholders' Equity	4,309,492	4,581,255
TOTAL LIABILITIES AND EQUITY	6,154,928	6,833,257
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	(21,614)
Other Guarantors Subsidiaries [Member]
Current Assets:
Cash and Cash Equivalents	0	0
Accounts and Notes Receivable:
Trade	72,295	59,321
Inventories	38,669	40,739
Income Taxes Receivable, Current	0	0
Prepaid Expenses	16,306	20,273
Other Receivables, Net, Current	14,516	3,330
Disposal Group, Including Discontinued Operation, Assets, Current	0	0
Total Current Assets	141,786	123,663
Property, Plant and Equipment:
Property, Plant and Equipment, Gross	3,928,861	3,898,005
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,997,687	1,854,249
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment		0
Total Property, Plant and Equipment-Net	1,931,174	2,043,756
Other Assets:
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	27,269	6,293
Other	114,030	95,369
Disposal Group, Including Discontinued Operation, Other Assets		0
Total Assets	2,214,259	2,269,081
Other Assets	141,299	101,662
Current Liabilities:
Other Accrued Liabilities, Current	223,705	218,186
Disposal Group, Including Discontinued Operation, Liabilities, Current	0	0
Accounts Payable	36,039	37,212
Accounts Payable (Recoverable)- Related Parties	(2,648,416)	(3,953,215)
Total Current Liabilities	(2,384,662)	(3,696,776)
Short-Term Notes Payable (Note 12)		0
Long-term Debt and Capital Lease Obligations, Including Current Maturities		105,611
Disposal Group, Including Discontinued Operation, Liabilities		0
Long-term Debt and Capital Lease Obligations	115,685	105,611
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent		0
Postretirement Benefits Other Than Pensions	659,474	630,892
Pneumoconiosis	106,016	109,969
Mine Closing	209,384	218,936
Gas Well Closing	27,549	28,572
Workers' Compensation	64,187	66,883
Salary Retirement	0	0
Reclamation		25
Other	15,663	4,266
Noncontrolling Interest in Limited Partnerships	0	0
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		0
Total deferred credits and other liabilities	1,082,273	1,059,543
Long-term Debt and Capital Lease Obligations, Current	4,010	1,041
Total CONSOL Energy Inc. Stockholders' Equity	3,400,963	4,800,703
TOTAL LIABILITIES AND EQUITY	2,214,259	2,269,081
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	0
Non-Guarantor Subsidiaries [Member]
Current Assets:
Cash and Cash Equivalents	885	970
Accounts and Notes Receivable:
Trade	0	0
Inventories	0	0
Income Taxes Receivable, Current	0	0
Prepaid Expenses	0	0
Other Receivables, Net, Current	0	0
Disposal Group, Including Discontinued Operation, Assets, Current	83	81,105
Total Current Assets	968	82,075
Property, Plant and Equipment:
Property, Plant and Equipment, Gross	0	0
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	0	0
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment		936,671
Total Property, Plant and Equipment-Net	0	936,671
Other Assets:
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Other	0	0
Disposal Group, Including Discontinued Operation, Other Assets		4,044
Total Assets	968	1,022,790
Other Assets	0	4,044
Current Liabilities:
Other Accrued Liabilities, Current	0	0
Disposal Group, Including Discontinued Operation, Liabilities, Current	6,050	51,514
Accounts Payable	0	0
Accounts Payable (Recoverable)- Related Parties	(209,491)	(209,452)
Total Current Liabilities	(203,441)	(157,938)
Short-Term Notes Payable (Note 12)		0
Long-term Debt and Capital Lease Obligations, Including Current Maturities		0
Disposal Group, Including Discontinued Operation, Liabilities		5,001
Long-term Debt and Capital Lease Obligations	0	5,001
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent		0
Postretirement Benefits Other Than Pensions	0	0
Pneumoconiosis	0	0
Mine Closing	0	0
Gas Well Closing	0	0
Workers' Compensation	0	0
Salary Retirement	0	0
Reclamation		0
Other	0	0
Noncontrolling Interest in Limited Partnerships	0	0
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		107,988
Total deferred credits and other liabilities	0	107,988
Long-term Debt and Capital Lease Obligations, Current	0	0
Total CONSOL Energy Inc. Stockholders' Equity	204,409	1,067,739
TOTAL LIABILITIES AND EQUITY	968	1,022,790
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	0
CNX Coal Resources LP [Member]
Current Assets:
Cash and Cash Equivalents	9,785	6,534
Accounts and Notes Receivable:
Trade	23,418	19,398
Inventories	11,491	12,238
Income Taxes Receivable, Current	0	0
Prepaid Expenses	3,512	5,089
Other Receivables, Net, Current	515	471
Disposal Group, Including Discontinued Operation, Assets, Current	0	0
Total Current Assets	48,721	43,730
Property, Plant and Equipment:
Property, Plant and Equipment, Gross	876,690	865,527
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	442,178	400,911
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment		0
Total Property, Plant and Equipment-Net	434,512	464,616
Other Assets:
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Other	21,063	17,598
Disposal Group, Including Discontinued Operation, Other Assets		0
Total Assets	504,296	525,944
Other Assets	21,063	17,598
Current Liabilities:
Other Accrued Liabilities, Current	44,230	37,220
Disposal Group, Including Discontinued Operation, Liabilities, Current	0	0
Accounts Payable	18,797	17,405
Accounts Payable (Recoverable)- Related Parties	1,666	4,310
Total Current Liabilities	64,781	58,996
Short-Term Notes Payable (Note 12)		0
Long-term Debt and Capital Lease Obligations, Including Current Maturities		181,070
Disposal Group, Including Discontinued Operation, Liabilities		0
Long-term Debt and Capital Lease Obligations	197,989	181,070
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent		0
Postretirement Benefits Other Than Pensions	0	0
Pneumoconiosis	2,057	1,934
Mine Closing	9,247	8,403
Gas Well Closing	99	96
Workers' Compensation	3,090	2,929
Salary Retirement	0	0
Reclamation		0
Other	463	713
Noncontrolling Interest in Limited Partnerships	0	0
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		0
Total deferred credits and other liabilities	14,956	14,075
Long-term Debt and Capital Lease Obligations, Current	88	61
Total CONSOL Energy Inc. Stockholders' Equity	226,570	271,803
TOTAL LIABILITIES AND EQUITY	504,296	525,944
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	0
Consolidation, Eliminations [Member]
Current Assets:
Cash and Cash Equivalents	0	0
Accounts and Notes Receivable:
Trade	0	0
Inventories	0	0
Income Taxes Receivable, Current	0	0
Prepaid Expenses	0	0
Other Receivables, Net, Current	0	0
Disposal Group, Including Discontinued Operation, Assets, Current	0	0
Total Current Assets	0	0
Property, Plant and Equipment:
Property, Plant and Equipment, Gross	0	0
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	0	0
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment		0
Total Property, Plant and Equipment-Net	0	0
Other Assets:
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	(7,998,941)	(10,567,751)
Other	0	0
Disposal Group, Including Discontinued Operation, Other Assets		0
Total Assets	(7,998,941)	(10,567,751)
Other Assets	(7,998,941)	(10,567,751)
Current Liabilities:
Other Accrued Liabilities, Current	0	0
Disposal Group, Including Discontinued Operation, Liabilities, Current	0	0
Accounts Payable	10,805	13,817
Accounts Payable (Recoverable)- Related Parties	(10,805)	(13,817)
Total Current Liabilities	0	0
Short-Term Notes Payable (Note 12)		0
Long-term Debt and Capital Lease Obligations, Including Current Maturities		0
Disposal Group, Including Discontinued Operation, Liabilities		0
Long-term Debt and Capital Lease Obligations	0	0
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent		0
Postretirement Benefits Other Than Pensions	0	0
Pneumoconiosis	0	0
Mine Closing	0	0
Gas Well Closing	0	0
Workers' Compensation	0	0
Salary Retirement	0	0
Reclamation		0
Other	0	0
Noncontrolling Interest in Limited Partnerships	142,493	153,749
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		0
Total deferred credits and other liabilities	0	0
Long-term Debt and Capital Lease Obligations, Current	0	0
Total CONSOL Energy Inc. Stockholders' Equity	(8,141,434)	(10,721,500)
TOTAL LIABILITIES AND EQUITY	(7,998,941)	$ (10,567,751)
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	$ 0