Guarantor Subsidiaries Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Jan. 02, 2013	Dec. 31, 2012	Jan. 02, 2012	Jan. 02, 2011
Current Assets:
Cash and Cash Equivalents	$ 176,989	$ 327,420	$ 327,420	$ 21,862	$ 21,862	$ 375,736
Accounts and Notes Receivable:
Trade	259,817	332,574
Notes, Loans and Financing Receivable, Net, Current	0	25,861
Other Receivables	347,146	243,973
Inventories	101,873	157,914
Deferred Income Taxes	66,569	211,303
Income Taxes Receivable, Current	20,401	10,705
Prepaid Expenses	193,555	135,842
Total Current Assets	1,166,350	1,445,592
Property, Plant and Equipment:
Property, Plant and Equipment, Gross	14,674,777	13,578,509
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	4,512,305	4,136,247
Total Property, Plant and Equipment-Net	10,162,472	9,442,262
Other Assets:
Investments in Unconsolidated Equity Affiliates	152,958	291,675
Notes, Loans and Financing Receivable, Net, Noncurrent	0	125
Other	277,750	214,013
Assets	11,759,530	11,393,667		12,997,594
Total Other Assets	430,708	505,813
Current Liabilities:
Accounts Payable	531,973	514,580
Accounts Payable (Recoverable)- Related Parties	0	0
Current Portion Long-Term Debt	13,016	11,455
Short-term Non-bank Loans and Notes Payable	0	0
Other Accrued Liabilities	602,972	565,697
Liabilities of Disposal Group, Including Discontinued Operation, Current	0	28,239
Total Current Liabilities	1,147,961	1,119,971
Long-Term Debt	3,236,422	3,115,963
Capital Lease Obligations	39,456	47,596
Long-Term Debt:	3,275,878	3,163,559
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent	325,592	242,643
Postretirement Benefits Other Than Pensions	703,680	961,127
Pneumoconiosis	116,941	111,971
Mine Closing	306,789	320,723
Gas Well Closing	175,369	175,603
Workers' Compensation	75,947	71,468
Salary Retirement	109,956	48,252
Reclamation	33,788	40,706
Other	158,171	131,355
Total deferred credits and other liabilities	2,006,233	2,103,848
Total CONSOL Energy Inc. Stockholders' Equity	5,329,458	5,006,289
TOTAL LIABILITIES AND EQUITY	11,759,530	11,393,667
Parent Issuer
Current Assets:
Cash and Cash Equivalents	145,239	320,473
Accounts and Notes Receivable:
Trade	0	0
Notes, Loans and Financing Receivable, Net, Current		1,238
Other Receivables	25,497	17,657
Inventories	0	0
Deferred Income Taxes	99,776	219,566
Income Taxes Receivable, Current	79,426	(16,262)
Prepaid Expenses	38,418	43,698
Total Current Assets	388,356	586,370
Property, Plant and Equipment:
Property, Plant and Equipment, Gross	158,555	173,719
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	108,432	122,022
Total Property, Plant and Equipment-Net	50,123	51,697
Other Assets:
Investments in Unconsolidated Equity Affiliates	12,571,886	11,965,054
Notes, Loans and Financing Receivable, Net, Noncurrent		125
Other	172,884	145,401
Assets	13,183,249	12,748,647
Total Other Assets	12,744,770	12,110,580
Current Liabilities:
Accounts Payable	86,313	91,553
Accounts Payable (Recoverable)- Related Parties	4,499,174	4,629,131
Current Portion Long-Term Debt	2,485	1,029
Short-term Non-bank Loans and Notes Payable	0	0
Other Accrued Liabilities	119,484	144,612
Liabilities of Disposal Group, Including Discontinued Operation, Current		0
Total Current Liabilities	4,707,456	4,866,325
Long-Term Debt	3,123,187	3,004,213
Capital Lease Obligations	942	1,245
Long-Term Debt:	3,124,129	3,005,458
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent	(148,925)	(232,904)
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	109,956	48,252
Reclamation	0	0
Other	61,175	55,227
Total deferred credits and other liabilities	22,206	(129,425)
Total CONSOL Energy Inc. Stockholders' Equity	5,329,458	5,006,289
TOTAL LIABILITIES AND EQUITY	13,183,249	12,748,647
Cnx Gas Guarantor [Member]
Current Assets:
Cash and Cash Equivalents	30,682	6,238
Accounts and Notes Receivable:
Trade	117,912	71,911
Notes, Loans and Financing Receivable, Net, Current		0
Other Receivables	309,247	207,128
Inventories	14,748	15,185
Deferred Income Taxes	(33,207)	(8,263)
Income Taxes Receivable, Current	(59,025)	26,967
Prepaid Expenses	129,796	65,701
Total Current Assets	510,153	384,867
Property, Plant and Equipment:
Property, Plant and Equipment, Gross	8,066,308	6,919,972
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,497,569	1,188,464
Total Property, Plant and Equipment-Net	6,568,739	5,731,508
Other Assets:
Investments in Unconsolidated Equity Affiliates	121,721	206,060
Notes, Loans and Financing Receivable, Net, Noncurrent		0
Other	71,339	30,728
Assets	7,271,952	6,353,163
Total Other Assets	193,060	236,788
Current Liabilities:
Accounts Payable	385,381	324,226
Accounts Payable (Recoverable)- Related Parties	182,758	23,287
Current Portion Long-Term Debt	6,602	6,258
Short-term Non-bank Loans and Notes Payable	720,150	332,487
Other Accrued Liabilities	172,787	89,080
Liabilities of Disposal Group, Including Discontinued Operation, Current		0
Total Current Liabilities	1,467,678	775,338
Long-Term Debt	0	0
Capital Lease Obligations	37,342	42,852
Long-Term Debt:	37,342	42,852
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent	474,517	475,547
Postretirement Benefits Other Than Pensions	0	0
Pneumoconiosis	0	0
Mine Closing	0	0
Gas Well Closing	116,930	119,429
Workers' Compensation	0	0
Salary Retirement	0	0
Reclamation	0	0
Other	94,378	61,190
Total deferred credits and other liabilities	685,825	656,166
Total CONSOL Energy Inc. Stockholders' Equity	5,081,107	4,878,807
TOTAL LIABILITIES AND EQUITY	7,271,952	6,353,163
Other Subsidiary Guarantors
Current Assets:
Cash and Cash Equivalents	0	0
Accounts and Notes Receivable:
Trade	0	0
Notes, Loans and Financing Receivable, Net, Current		24,623
Other Receivables	12,390	14,969
Inventories	87,125	99,320
Deferred Income Taxes	0	0
Income Taxes Receivable, Current	0	0
Prepaid Expenses	25,341	24,915
Total Current Assets	124,856	163,827
Property, Plant and Equipment:
Property, Plant and Equipment, Gross	6,449,914	6,459,014
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	2,906,304	2,806,775
Total Property, Plant and Equipment-Net	3,543,610	3,652,239
Other Assets:
Investments in Unconsolidated Equity Affiliates	27,544	70,222
Notes, Loans and Financing Receivable, Net, Noncurrent		0
Other	33,527	28,831
Assets	3,729,537	3,915,119
Total Other Assets	61,071	99,053
Current Liabilities:
Accounts Payable	60,279	89,201
Accounts Payable (Recoverable)- Related Parties	(5,333,209)	(5,121,727)
Current Portion Long-Term Debt	3,929	3,372
Short-term Non-bank Loans and Notes Payable	0	0
Other Accrued Liabilities	310,701	322,606
Liabilities of Disposal Group, Including Discontinued Operation, Current		0
Total Current Liabilities	(4,958,300)	(4,706,548)
Long-Term Debt	113,235	111,750
Capital Lease Obligations	1,172	1,724
Long-Term Debt:	114,407	113,474
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent	0	0
Postretirement Benefits Other Than Pensions	703,680	961,127
Pneumoconiosis	116,941	111,971
Mine Closing	306,789	320,723
Gas Well Closing	58,439	56,174
Workers' Compensation	75,947	71,136
Salary Retirement	0	0
Reclamation	33,788	40,706
Other	2,618	14,938
Total deferred credits and other liabilities	1,298,202	1,576,775
Total CONSOL Energy Inc. Stockholders' Equity	7,275,228	6,931,418
TOTAL LIABILITIES AND EQUITY	3,729,537	3,915,119
Non-Guarantors
Current Assets:
Cash and Cash Equivalents	1,068	709
Accounts and Notes Receivable:
Trade	141,905	260,663
Notes, Loans and Financing Receivable, Net, Current		0
Other Receivables	12	4,219
Inventories	0	43,409
Deferred Income Taxes	0	0
Income Taxes Receivable, Current	0	0
Prepaid Expenses	0	1,528
Total Current Assets	142,985	310,528
Property, Plant and Equipment:
Property, Plant and Equipment, Gross	0	25,804
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	0	18,986
Total Property, Plant and Equipment-Net	0	6,818
Other Assets:
Investments in Unconsolidated Equity Affiliates	0	0
Notes, Loans and Financing Receivable, Net, Noncurrent		0
Other	0	9,053
Assets	142,985	326,399
Total Other Assets	0	9,053
Current Liabilities:
Accounts Payable	0	9,600
Accounts Payable (Recoverable)- Related Parties	(68,873)	136,822
Current Portion Long-Term Debt	0	796
Short-term Non-bank Loans and Notes Payable	0	0
Other Accrued Liabilities	0	9,399
Liabilities of Disposal Group, Including Discontinued Operation, Current		28,239
Total Current Liabilities	(68,873)	184,856
Long-Term Debt	0	0
Capital Lease Obligations	0	1,775
Long-Term Debt:	0	1,775
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent	0	0
Postretirement Benefits Other Than Pensions	0	0
Pneumoconiosis	0	0
Mine Closing	0	0
Gas Well Closing	0	0
Workers' Compensation	0	332
Salary Retirement	0	0
Reclamation	0	0
Other	0	0
Total deferred credits and other liabilities	0	332
Total CONSOL Energy Inc. Stockholders' Equity	211,858	139,436
TOTAL LIABILITIES AND EQUITY	142,985	326,399
Elimination
Current Assets:
Cash and Cash Equivalents	0	0
Accounts and Notes Receivable:
Trade	0	0
Notes, Loans and Financing Receivable, Net, Current		0
Other Receivables	0	0
Inventories	0	0
Deferred Income Taxes	0	0
Income Taxes Receivable, Current	0	0
Prepaid Expenses	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
Total Property, Plant and Equipment-Net	0	0
Other Assets:
Investments in Unconsolidated Equity Affiliates	(12,568,193)	(11,949,661)
Notes, Loans and Financing Receivable, Net, Noncurrent		0
Other	0	0
Assets	(12,568,193)	(11,949,661)
Total Other Assets	(12,568,193)	(11,949,661)
Current Liabilities:
Accounts Payable	0	0
Accounts Payable (Recoverable)- Related Parties	720,150	332,487
Current Portion Long-Term Debt	0	0
Short-term Non-bank Loans and Notes Payable	(720,150)	(332,487)
Other Accrued Liabilities	0	0
Liabilities of Disposal Group, Including Discontinued Operation, Current		0
Total Current Liabilities	0	0
Capital Lease Obligations	0	0
Long-Term Debt:	0	0
Deferred Credits and Other Liabilities
Deferred Tax Liabilities, Net, Noncurrent	0	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	0
Other	0	0
Total deferred credits and other liabilities	0	0
Total CONSOL Energy Inc. Stockholders' Equity	(12,568,193)	(11,949,661)
TOTAL LIABILITIES AND EQUITY	$ (12,568,193)	$ (11,949,661)