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Goodwill and Other Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Dec. 31, 2017	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Jan. 03, 2018
Goodwill [Line Items]
Goodwill		$ 323,314	$ 323,314	$ 323,314	$ 796,359
Impairment of goodwill		$ 0	473,045
Useful life, customer relationship intangible assets		17 years
Amortization expense		$ 1,638	$ 1,638
Estimated annual amortization expense, Year 2021		6,552
Estimated annual amortization expense, Year 2022		6,552
Estimated annual amortization expense, Year 2023		6,552
Estimated annual amortization expense, Year 2024		6,552
Estimated annual amortization expense, Year 2025		$ 6,552
Midstream Acquisition
Goodwill [Line Items]
Cash consideration transferred	$ 305,000
Fair value of previously held equity interest	$ 799,033
Goodwill						$ 796,359
Other intangible assets						$ 128,781
CNX Gathering LLC
Goodwill [Line Items]
Ownership percentage in equity method investment	50.00%