Revolving Credit Facilities (Details)	1 Months Ended	9 Months Ended
	Apr. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Oct. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)
Short-term Debt [Line Items]
Number of days outstanding, prior to springing maturity date		91 days
Value of proved reserves, percentage to mortgage		80.00%
Value of proved developing producing reserves, percentage to mortgage		80.00%
Revolving Credit Facility
Short-term Debt [Line Items]
Debt instrument, face amount	$ 2,100,000,000	$ 160,000
Accordion feature, increased commitment	3,000,000,000
Initial borrowing base	2,100,000,000
Letters of credit aggregate sub-limit	$ 650,000,000
Net leverage ratio	3.00
Percentage of aggregate commitments available under credit facility	15.00%
Minimum threshold to activate springing maturity date		$ 500,000,000
Minimum current ratio		1.00
Borrowings outstanding		$ 613,200,000		$ 612,000,000
Letters of credit outstanding		199,066,000		198,396,000
Borrowings and issuance of letters of credit remaining capacity		$ 1,287,734,000		1,289,604,000
Maximum | Revolving Credit Facility
Short-term Debt [Line Items]
Net leverage ratio		4.00
5.875% Senior Notes due 2022
Short-term Debt [Line Items]
Stated rate, debt instrument		5.875%
CNXM | Revolving Credit Facility
Short-term Debt [Line Items]
Letters of credit aggregate sub-limit	$ 600,000,000
Increase in available borrowings	$ 250,000,000
Borrowings outstanding		$ 246,000,000		$ 84,000,000
Borrowings and issuance of letters of credit remaining capacity		$ 354,000,000
Secured leverage ratio		3.00
Total leverage ratio		4.00
Pro forma availability of commitments, percentage		20.00%
Basket for repurchase of LP units tied to Available Cash, annual limit		$ 150,000
Basket for repurchase of LP units tied to Available Cash, lifetime limit		200,000
Maximum borrowing capacity, letters of credit		$ 100,000,000
Interest coverage ratio		2.50
CNXM | Minimum | Revolving Credit Facility
Short-term Debt [Line Items]
Total leverage ratio		4.75
Maximum net leverage ratio		5.25
CNXM | Maximum | Revolving Credit Facility
Short-term Debt [Line Items]
Secured leverage ratio		3.50
Total leverage ratio		5.25
Maximum net leverage ratio		5.50
CNXM | 5.875% Senior Notes due 2022 | Minimum
Short-term Debt [Line Items]
Debt instrument, face amount		$ 150,000,000
CNXM | 5.875% Senior Notes due 2022 | Maximum
Short-term Debt [Line Items]
Debt instrument, face amount					$ 150,000,000
Federal Funds Open Rate
Short-term Debt [Line Items]
Basis spread on variable rate		0.50%
Federal Funds Open Rate | CNXM
Short-term Debt [Line Items]
Basis spread on variable rate		0.50%
One-Month LIBOR
Short-term Debt [Line Items]
Basis spread on variable rate		1.00%
One-Month LIBOR | Minimum
Short-term Debt [Line Items]
Basis spread on variable rate		0.25%
One-Month LIBOR | Maximum
Short-term Debt [Line Items]
Basis spread on variable rate		1.25%
One-Month LIBOR | CNXM
Short-term Debt [Line Items]
Basis spread on variable rate		1.00%
One-Month LIBOR | CNXM | Minimum
Short-term Debt [Line Items]
Basis spread on variable rate		0.50%
One-Month LIBOR | CNXM | Maximum
Short-term Debt [Line Items]
Basis spread on variable rate		1.50%
London Interbank Offered Rate (LIBOR) | Minimum
Short-term Debt [Line Items]
Basis spread on variable rate		1.25%
London Interbank Offered Rate (LIBOR) | Maximum
Short-term Debt [Line Items]
Basis spread on variable rate		2.25%
London Interbank Offered Rate (LIBOR) | CNXM | Minimum
Short-term Debt [Line Items]
Basis spread on variable rate		1.50%
London Interbank Offered Rate (LIBOR) | CNXM | Maximum
Short-term Debt [Line Items]
Basis spread on variable rate		2.50%
Subsequent Event | Revolving Credit Facility
Short-term Debt [Line Items]
Initial borrowing base			$ 2,300,000,000