(Guarantor Subsidiaries Balance Sheet) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current Assets:
Cash and Cash Equivalents	$ 235,677	$ 153,979
Accounts and Notes Receivable:
Trade	87,589	131,545
Other Receivables	41,355	36,552
Inventories	48,646	53,420
Prepaid Expenses and Other Assets	60,688	23,744
Total Current Assets	473,955	399,240
Property, Plant and Equipment:
Property, Plant and Equipment	4,838,171	4,676,353
Less: Accumulated Depreciation, Depletion and Amortization	2,731,643	2,554,056
Total Property, Plant and Equipment—Net	2,106,528	2,122,297
Other Assets:
Deferred Income Taxes	77,545	75,065
Affiliated Credit Facility	0	0
Investment in Affiliates	0	0
Other	102,699	110,497
Total Other Assets	180,244	185,562
TOTAL ASSETS	2,760,727	2,707,099	$ 2,687,434
Current Liabilities:
Accounts Payable	130,930	109,100
Accounts Payable (Recoverable)-Related Parties	0	0
Current Portion of Long-Term Debt	134,812	22,482
Other Accrued Liabilities	226,434	290,627
Total Current Liabilities	492,176	422,209
Total Long-Term Debt	734,226	865,289
Deferred Credits and Other Liabilities:
Postretirement Benefits Other Than Pensions	441,246	554,099
Pneumoconiosis Benefits	165,001	149,868
Asset Retirement Obligations	235,984	228,343
Workers’ Compensation	59,742	66,648
Salary Retirement	64,172	52,960
Other	16,569	24,042
Total Deferred Credits and Other Liabilities	982,714	1,075,960
Total CONSOL Energy Inc. Stockholders' Equity	409,935	204,260
Noncontrolling Interest	141,676	139,381
TOTAL LIABILITIES AND EQUITY	2,760,727	2,707,099
Elimination
Current Assets:
Cash and Cash Equivalents	0	0
Accounts and Notes Receivable:
Trade	0	0
Other Receivables	0	0
Inventories	0	0
Prepaid Expenses and Other Assets	0	0
Total Current Assets	0	0
Property, Plant and Equipment:
Property, Plant and Equipment	0	0
Less: Accumulated Depreciation, Depletion and Amortization	0	0
Total Property, Plant and Equipment—Net	0	0
Other Assets:
Deferred Income Taxes	0	0
Affiliated Credit Facility	(141,129)	(165,110)
Investment in Affiliates	(605,981)	(645,157)
Other	0	0
Total Other Assets	(747,110)	(810,267)
TOTAL ASSETS	(747,110)	(810,267)
Current Liabilities:
Accounts Payable	3,822	18
Accounts Payable (Recoverable)-Related Parties	(125,353)	(163,069)
Current Portion of Long-Term Debt	112,013	0
Other Accrued Liabilities	(3,822)	(4,874)
Total Current Liabilities	(13,340)	(167,925)
Total Long-Term Debt	(141,129)	(165,110)
Deferred Credits and Other Liabilities:
Postretirement Benefits Other Than Pensions	0	0
Pneumoconiosis Benefits	0	0
Asset Retirement Obligations	0	0
Workers’ Compensation	0	0
Salary Retirement	0	0
Other	0	0
Total Deferred Credits and Other Liabilities	0	0
Total CONSOL Energy Inc. Stockholders' Equity	(734,317)	(616,613)
Noncontrolling Interest	141,676	139,381
TOTAL LIABILITIES AND EQUITY	(747,110)	(810,267)
Parent Issuer | Reportable Legal Entities
Current Assets:
Cash and Cash Equivalents	234,536	152,235
Accounts and Notes Receivable:
Trade	0	0
Other Receivables	24,352	17,702
Inventories	0	0
Prepaid Expenses and Other Assets	25,440	5,745
Total Current Assets	284,328	175,682
Property, Plant and Equipment:
Property, Plant and Equipment	0	0
Less: Accumulated Depreciation, Depletion and Amortization	0	0
Total Property, Plant and Equipment—Net	0	0
Other Assets:
Deferred Income Taxes	77,545	75,065
Affiliated Credit Facility	141,129	165,110
Investment in Affiliates	605,981	645,157
Other	40,760	44,177
Total Other Assets	865,415	929,509
TOTAL ASSETS	1,149,743	1,105,191
Current Liabilities:
Accounts Payable	(721)	20,014
Accounts Payable (Recoverable)-Related Parties	(2,291)	(2,291)
Current Portion of Long-Term Debt	8,157	0
Other Accrued Liabilities	92,534	101,994
Total Current Liabilities	97,679	119,717
Total Long-Term Debt	577,957	728,254
Deferred Credits and Other Liabilities:
Postretirement Benefits Other Than Pensions	0	0
Pneumoconiosis Benefits	0	0
Asset Retirement Obligations	0	0
Workers’ Compensation	0	0
Salary Retirement	64,172	52,960
Other	0	0
Total Deferred Credits and Other Liabilities	64,172	52,960
Total CONSOL Energy Inc. Stockholders' Equity	409,935	204,260
Noncontrolling Interest	0	0
TOTAL LIABILITIES AND EQUITY	1,149,743	1,105,191
Guarantor | Reportable Legal Entities
Current Assets:
Cash and Cash Equivalents	138	105
Accounts and Notes Receivable:
Trade	0	0
Other Receivables	15,935	16,880
Inventories	37,580	41,117
Prepaid Expenses and Other Assets	15,451	13,568
Total Current Assets	69,104	71,670
Property, Plant and Equipment:
Property, Plant and Equipment	3,891,873	3,765,885
Less: Accumulated Depreciation, Depletion and Amortization	2,204,896	2,070,646
Total Property, Plant and Equipment—Net	1,686,977	1,695,239
Other Assets:
Deferred Income Taxes	0	0
Affiliated Credit Facility	0	0
Investment in Affiliates	0	0
Other	47,031	50,846
Total Other Assets	47,031	50,846
TOTAL ASSETS	1,803,112	1,817,755
Current Liabilities:
Accounts Payable	102,995	66,271
Accounts Payable (Recoverable)-Related Parties	36,220	36,221
Current Portion of Long-Term Debt	11,139	22,405
Other Accrued Liabilities	105,806	149,425
Total Current Liabilities	256,160	274,322
Total Long-Term Debt	151,202	135,390
Deferred Credits and Other Liabilities:
Postretirement Benefits Other Than Pensions	441,246	554,099
Pneumoconiosis Benefits	160,741	146,035
Asset Retirement Obligations	226,209	218,728
Workers’ Compensation	56,623	63,244
Salary Retirement	0	0
Other	16,051	23,435
Total Deferred Credits and Other Liabilities	900,870	1,005,541
Total CONSOL Energy Inc. Stockholders' Equity	494,880	402,502
Noncontrolling Interest	0	0
TOTAL LIABILITIES AND EQUITY	1,803,112	1,817,755
Non-Guarantor | Reportable Legal Entities
Current Assets:
Cash and Cash Equivalents	0	106
Accounts and Notes Receivable:
Trade	87,589	131,545
Other Receivables	0	0
Inventories	0	0
Prepaid Expenses and Other Assets	14,701	3
Total Current Assets	102,290	131,654
Property, Plant and Equipment:
Property, Plant and Equipment	0	0
Less: Accumulated Depreciation, Depletion and Amortization	0	0
Total Property, Plant and Equipment—Net	0	0
Other Assets:
Deferred Income Taxes	0	0
Affiliated Credit Facility	0	0
Investment in Affiliates	0	0
Other	0	0
Total Other Assets	0	0
TOTAL ASSETS	102,290	131,654
Current Liabilities:
Accounts Payable	0	8
Accounts Payable (Recoverable)-Related Parties	87,593	129,139
Current Portion of Long-Term Debt	0	0
Other Accrued Liabilities	0	(20)
Total Current Liabilities	87,593	129,127
Total Long-Term Debt	0	1,572
Deferred Credits and Other Liabilities:
Postretirement Benefits Other Than Pensions	0	0
Pneumoconiosis Benefits	0	0
Asset Retirement Obligations	0	0
Workers’ Compensation	0	0
Salary Retirement	0	0
Other	0	0
Total Deferred Credits and Other Liabilities	0	0
Total CONSOL Energy Inc. Stockholders' Equity	14,697	955
Noncontrolling Interest	0	0
TOTAL LIABILITIES AND EQUITY	102,290	131,654
CONSOL Coal Resources LP | Non-Guarantor | Reportable Legal Entities
Current Assets:
Cash and Cash Equivalents	1,003	1,533
Accounts and Notes Receivable:
Trade	0	0
Other Receivables	1,068	1,970
Inventories	11,066	12,303
Prepaid Expenses and Other Assets	5,096	4,428
Total Current Assets	18,233	20,234
Property, Plant and Equipment:
Property, Plant and Equipment	946,298	910,468
Less: Accumulated Depreciation, Depletion and Amortization	526,747	483,410
Total Property, Plant and Equipment—Net	419,551	427,058
Other Assets:
Deferred Income Taxes	0	0
Affiliated Credit Facility	0	0
Investment in Affiliates	0	0
Other	14,908	15,474
Total Other Assets	14,908	15,474
TOTAL ASSETS	452,692	462,766
Current Liabilities:
Accounts Payable	24,834	22,789
Accounts Payable (Recoverable)-Related Parties	3,831	0
Current Portion of Long-Term Debt	3,503	77
Other Accrued Liabilities	31,916	44,102
Total Current Liabilities	64,084	66,968
Total Long-Term Debt	146,196	165,183
Deferred Credits and Other Liabilities:
Postretirement Benefits Other Than Pensions	0	0
Pneumoconiosis Benefits	4,260	3,833
Asset Retirement Obligations	9,775	9,615
Workers’ Compensation	3,119	3,404
Salary Retirement	0	0
Other	518	607
Total Deferred Credits and Other Liabilities	17,672	17,459
Total CONSOL Energy Inc. Stockholders' Equity	224,740	213,156
Noncontrolling Interest	0	0
TOTAL LIABILITIES AND EQUITY	$ 452,692	$ 462,766