Note 17 - Additional Information With Respect to Unrestricted Subsidiaries - Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Cash and Cash Equivalents	$ 22,284	$ 80,293
Trade Receivables, net	120,548	131,688
Other Receivables, net	24,748	40,984
Inventories	56,577	54,131
Prepaid Expenses and Other Assets	27,139	30,933
Total Current Assets	251,296	338,029
Property, Plant and Equipment	5,126,703	5,008,180
Less - Accumulated Depreciation, Depletion and Amortization	3,043,463	2,916,015
Total Property, Plant and Equipment - Net	2,083,240	2,092,165
Deferred Income Taxes	101,639	103,505	$ 91,772
Right of Use Asset - Operating Leases	58,106	72,632
Other, net	60,557	87,471
Total Other Assets	220,302	263,608
TOTAL ASSETS	2,554,838	2,693,802	$ 2,723,235
Accounts Payable	72,263	106,223
Accounts (Recoverable) Payable - Related Parties	0	0
Current Portion of Long-Term Debt	68,954	50,272
Other Accrued Liabilities	247,395	235,769
Total Current Liabilities	388,612	392,264
Long-Term Debt, Related Party	0	0
Long-Term Debt, Related Party	0	0
Long-Term Debt	587,020	653,802
Finance Lease Obligations	21,146	9,036
Total Long-Term Debt	608,166	662,838
Postretirement Benefits Other Than Pensions	421,705	432,496
Pneumoconiosis Benefits	201,066	202,142
Asset Retirement Obligations	229,346	250,211
Workers’ Compensation	61,525	61,194
Salary Retirement	33,454	49,930
Operating Lease Liability	41,623	55,413
Other	16,613	14,919
Total Deferred Credits and Other Liabilities	1,005,332	1,066,305
TOTAL LIABILITIES	2,002,110	2,121,407
Total CONSOL Energy Inc. Stockholders’ Equity	426,079	435,199
Noncontrolling Interest	126,649	137,196
TOTAL LIABILITIES AND EQUITY	2,554,838	2,693,802
Parent Company and Restricted Subsidiaries [Member]
Cash and Cash Equivalents	21,636	79,717
Trade Receivables, net	0	0
Other Receivables, net	23,786	39,412
Inventories	43,399	41,478
Prepaid Expenses and Other Assets	23,053	25,181
Total Current Assets	111,874	185,788
Property, Plant and Equipment	4,109,220	4,023,282
Less - Accumulated Depreciation, Depletion and Amortization	2,437,152	2,344,777
Total Property, Plant and Equipment - Net	1,672,068	1,678,505
Deferred Income Taxes	101,639	103,505
Right of Use Asset - Operating Leases	45,936	56,937
Other, net	57,920	74,015
Total Other Assets	205,495	234,457
TOTAL ASSETS	1,989,437	2,098,750
Accounts Payable	51,277	79,140
Accounts (Recoverable) Payable - Related Parties	(8,035)	(1,419)
Current Portion of Long-Term Debt	59,703	45,020
Other Accrued Liabilities	209,132	196,314
Total Current Liabilities	312,077	319,055
Long-Term Debt, Related Party	(174,685)	(148,156)
Long-Term Debt, Related Party	174,685	148,156
Long-Term Debt	587,020	653,802
Finance Lease Obligations	15,948	7,391
Total Long-Term Debt	428,283	513,037
Postretirement Benefits Other Than Pensions	421,705	432,496
Pneumoconiosis Benefits	194,312	196,114
Asset Retirement Obligations	218,031	239,410
Workers’ Compensation	57,527	57,583
Salary Retirement	33,454	49,930
Operating Lease Liability	33,445	43,906
Other	15,726	14,134
Total Deferred Credits and Other Liabilities	974,200	1,033,573
TOTAL LIABILITIES	1,714,560	1,865,665
Total CONSOL Energy Inc. Stockholders’ Equity	148,228	95,889
Noncontrolling Interest	126,649	137,196
TOTAL LIABILITIES AND EQUITY	1,989,437	2,098,750
Subsidiaries [Member]
Cash and Cash Equivalents	648	576
Trade Receivables, net	120,548	131,688
Other Receivables, net	962	1,572
Inventories	13,178	12,653
Prepaid Expenses and Other Assets	4,086	5,752
Total Current Assets	139,422	152,241
Property, Plant and Equipment	1,017,483	984,898
Less - Accumulated Depreciation, Depletion and Amortization	606,311	571,238
Total Property, Plant and Equipment - Net	411,172	413,660
Deferred Income Taxes	0	0
Right of Use Asset - Operating Leases	12,170	15,695
Other, net	2,637	13,456
Total Other Assets	14,807	29,151
TOTAL ASSETS	565,401	595,052
Accounts Payable	20,986	27,083
Accounts (Recoverable) Payable - Related Parties	8,035	1,419
Current Portion of Long-Term Debt	9,251	5,252
Other Accrued Liabilities	38,263	39,455
Total Current Liabilities	76,535	73,209
Long-Term Debt, Related Party	174,685	(148,156)
Long-Term Debt, Related Party	(174,685)	148,156
Long-Term Debt	0	0
Finance Lease Obligations	5,198	1,645
Total Long-Term Debt	179,883	149,801
Postretirement Benefits Other Than Pensions	0	0
Pneumoconiosis Benefits	6,754	6,028
Asset Retirement Obligations	11,315	10,801
Workers’ Compensation	3,998	3,611
Salary Retirement	0	0
Operating Lease Liability	8,178	11,507
Other	887	785
Total Deferred Credits and Other Liabilities	31,132	32,732
TOTAL LIABILITIES	287,550	255,742
Total CONSOL Energy Inc. Stockholders’ Equity	277,851	339,310
Noncontrolling Interest	0	0
TOTAL LIABILITIES AND EQUITY	$ 565,401	$ 595,052