Note 24 - Related Party Transactions (Details Textual)			1 Months Ended	9 Months Ended	12 Months Ended
		Jun. 05, 2020	Aug. 31, 2019 shares	Sep. 30, 2020 shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Nov. 28, 2019	May 31, 2019 USD ($)	Nov. 28, 2017 USD ($)
Payment of Separation and Distribution Costs							$ 18,234,000
Separation, Number of Independent Businesses							2
Stock Issued During Period, Shares, Acquisitions (in shares) | shares	[1]				7,967,690	0	0
Common Unit Shares Issued Upon Conversion			1
CONSOL Coal Resources L P Units Member
Conversion of Stock, Shares Converted (in shares) | shares			11,611,067
Stock and Debt Repurchase Program, Restricted Authorized Amount									$ 50,000,000
CONSOL Coal Resources L P [Member]
Stock Purchased During Period, Affiliated Entity Units (in shares) | shares				0	0	26,297	167,958
Stock Purchased, Affiliated Entity, Average Cost Per Share (in dollars per share) | $ / shares						$ 14.05	$ 18.33
CONSOL Coal Resources L P [Member]
Common Unit, Issued (in shares) | shares					10,912,138
Common Stock, Fixed Exchange Ratio					0.73
Conversion of Stock, Amount Converted					$ 51,710
Accounts Payable, Related Parties, Current						$ 1,419,000
Stock and Debt Repurchase Program, Restricted Authorized Amount									$ 50,000,000
CNX Resources Corporation [Member]
Notes Receivable, Related Parties						6,791,000
Affiliated Company Credit Agreement [Member] | Affiliated Entity [Member]
Line of Credit Facility, Maximum Borrowing Capacity										$ 275,000,000
Long-term Line of Credit, Total										201,000,000
Affiliated Company Credit Agreement [Member] | Affiliated Entity [Member] | Senior Secured Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity										$ 400,000,000
Debt Instrument, Interest Rate, Increase (Decrease)		50.00%
Affiliated Company Credit Agreement [Member] | CONSOL Coal Resources L P [Member] | Affiliated Entity [Member]
Common Unit, Issued (in shares) | shares					37,322,410,000
Interest Expense, Related Party					$ 9,155,000	$ 7,892,000	$ 7,709,000
Repayments of Long-term Debt, Total					$ 176,535,000
Affiliated Company Credit Agreement [Member] | CONSOL Coal Resources L P [Member] | Affiliated Entity [Member] | Minimum [Member]
Debt Instrument, Interest Rate, Stated Percentage								4.25%
Affiliated Company Credit Agreement [Member] | CONSOL Coal Resources L P [Member] | Affiliated Entity [Member] | Maximum [Member]
Debt Instrument, Interest Rate, Stated Percentage								5.25%

[1] See Note 2 - Major Transactions for additional information.