SUBSEQUENT EVENTS - Narrative (Details) $ / shares in Units, $ in Millions		1 Months Ended
	Oct. 15, 2020 $ / shares	Oct. 31, 2020 USD ($)	Nov. 09, 2020 shares	Nov. 03, 2020 shares	Oct. 30, 2020 shares	Sep. 30, 2020 shares	Dec. 31, 2019 shares
Subsequent Event [Line Items]
Common limited partner capital (in shares), outstanding						56,624,887	45,318,866
Subsequent Event | Summit Midstream GP, LLC | Reverse Unit Split
Subsequent Event [Line Items]
Reverse unit split ratio	0.06
Reverse unit split description	On October 15, 2020, the Board of Directors of the General Partner authorized a reverse unit split (the “Reverse Unit Split”) of the Partnership’s common units.  The exchange ratio of the Reverse Unit Split is 1-for-15 and will be effective on November 9, 2020. The common units will begin trading on a split-adjusted basis on November 10, 2020.
Common limited partner capital (in shares), outstanding			3,774,992		56,624,887
Subsequent Event | Summit Midstream GP, LLC | NYSE | Reverse Unit Split
Subsequent Event [Line Items]
Minimum bid price for continued listing | $ / shares	$ 1.00
Subsequent Event | TL Restructuring | SMP Holding
Subsequent Event [Line Items]
Percent of term loan lenders agree to term loan restructuring		100.00%
Common units issued to the lenders of term loan				34,600,000
2025 Senior Notes | Subsequent Event
Subsequent Event [Line Items]
Senior notes repurchased | $		$ 95.6
Total cash consideration | $		$ 64.8