EARNINGS PER UNIT (Tables)

3 Months Ended

Mar. 31, 2021

Earnings Per Share [Abstract]

Schedule of earnings per limited partner unit

The following table details the components of EPU.

	Three Months Ended March 31,
	2021			2020
	(In thousands, except per-unit amounts)
Numerator for basic and diluted EPU:
Allocation of net income (loss) among limited partner interests:
Net income (loss)	$	8,988		$	3,762
Net (income) loss attributable to Subsidiary Series A Preferred Units		(3,932	)		(945	)
Net loss attributable to noncontrolling interest		—			1,881
Net income (loss) attributable to Summit Midstream Partners, LP		5,056			4,698
Less: Net income attributable to Series A Preferred Units		(4,287	)		(7,125	)
Net income (loss) attributable to common limited partners	$	769		$	(2,427	)
Denominator for basic and diluted EPU:
Weighted-average common units outstanding – basic		6,125			3,021
Effect of nonvested phantom units		135			—
Weighted-average common units outstanding – diluted		6,260			3,021
Net Income (Loss) per limited partner unit:
Common unit – basic	$	0.13		$	(0.80	)
Common unit – diluted	$	0.12		$	(0.80	)
Nonvested anti-dilutive phantom units excluded from the     calculation of diluted EPU		44			126