CONDENSED CONSOLIDATING FINANCIAL INFORMATION - Condensed Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Gathering services and related fees	$ 84,361	$ 118,013
Natural gas, NGLs and condensate sales	26,117	11,120
Other revenues	6,842	6,672
Total revenues	117,320	135,805
Costs and expenses:
Cost of natural gas and NGLs	20,286	9,052
Operation and maintenance	24,604	23,692
General and administrative	14,385	14,132
Depreciation and amortization	26,677	28,569
Transaction costs	57	0
(Gain) loss on asset sales, net	(74)	3
Long-lived asset impairment	0	284
Total costs and expenses	85,935	75,732
Other (expense) income	(7)	71
Interest expense	(15,122)	(16,716)
Early extinguishment of debt	0	(22,020)
Deferred Purchase Price Obligation	(21,658)	(20,883)
(Loss) income before income taxes and income (loss) from equity method investees	(5,402)	525
Income tax benefit (expense)	171	(452)
Income (loss) from equity method investees	1,386	(656)
Equity in earnings of consolidated subsidiaries	0	0
Net loss	(3,845)	(583)
Consolidating adjustments
Revenues:
Gathering services and related fees	0	0
Natural gas, NGLs and condensate sales	0	0
Other revenues	0	0
Total revenues	0	0
Costs and expenses:
Cost of natural gas and NGLs	0	0
Operation and maintenance	0	0
General and administrative	0	0
Depreciation and amortization	0	0
Transaction costs	0
(Gain) loss on asset sales, net	0	0
Long-lived asset impairment		0
Total costs and expenses	0	0
Other (expense) income	0	0
Interest expense	0	0
Early extinguishment of debt		0
Deferred Purchase Price Obligation	0	0
(Loss) income before income taxes and income (loss) from equity method investees	0	0
Income tax benefit (expense)	0	0
Income (loss) from equity method investees	0	0
Equity in earnings of consolidated subsidiaries	(51,398)	(80,406)
Net loss	(51,398)	(80,406)
Summit Midstream Partners, LP | Reportable Legal Entities
Revenues:
Gathering services and related fees	0	0
Natural gas, NGLs and condensate sales	0	0
Other revenues	0	0
Total revenues	0	0
Costs and expenses:
Cost of natural gas and NGLs	0	0
Operation and maintenance	0	0
General and administrative	0	0
Depreciation and amortization	432	154
Transaction costs	57
(Gain) loss on asset sales, net	0	0
Long-lived asset impairment		0
Total costs and expenses	489	154
Other (expense) income	(7)	71
Interest expense	0	0
Early extinguishment of debt		0
Deferred Purchase Price Obligation	(21,658)	(20,883)
(Loss) income before income taxes and income (loss) from equity method investees	(22,154)	(20,966)
Income tax benefit (expense)	171	(452)
Income (loss) from equity method investees	0	0
Equity in earnings of consolidated subsidiaries	18,138	20,835
Net loss	(3,845)	(583)
Co-Issuers | Reportable Legal Entities
Revenues:
Gathering services and related fees	0	0
Natural gas, NGLs and condensate sales	0	0
Other revenues	0	0
Total revenues	0	0
Costs and expenses:
Cost of natural gas and NGLs	0	0
Operation and maintenance	0	0
General and administrative	0	0
Depreciation and amortization	0	0
Transaction costs	0
(Gain) loss on asset sales, net	0	0
Long-lived asset impairment		0
Total costs and expenses	0	0
Other (expense) income	0	0
Interest expense	(15,122)	(16,716)
Early extinguishment of debt		(22,020)
Deferred Purchase Price Obligation	0	0
(Loss) income before income taxes and income (loss) from equity method investees	(15,122)	(38,736)
Income tax benefit (expense)	0	0
Income (loss) from equity method investees	0	0
Equity in earnings of consolidated subsidiaries	33,260	59,571
Net loss	18,138	20,835
Guarantor Subsidiaries | Reportable Legal Entities
Revenues:
Gathering services and related fees	69,466	102,513
Natural gas, NGLs and condensate sales	26,117	11,120
Other revenues	6,727	6,600
Total revenues	102,310	120,233
Costs and expenses:
Cost of natural gas and NGLs	20,286	9,052
Operation and maintenance	22,153	22,020
General and administrative	12,287	12,485
Depreciation and amortization	22,861	25,242
Transaction costs	0
(Gain) loss on asset sales, net	(74)	3
Long-lived asset impairment		0
Total costs and expenses	77,513	68,802
Other (expense) income	0	0
Interest expense	0	0
Early extinguishment of debt		0
Deferred Purchase Price Obligation	0	0
(Loss) income before income taxes and income (loss) from equity method investees	24,797	51,431
Income tax benefit (expense)	0	0
Income (loss) from equity method investees	0	0
Equity in earnings of consolidated subsidiaries	0	0
Net loss	24,797	51,431
Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenues:
Gathering services and related fees	14,895	15,500
Natural gas, NGLs and condensate sales	0	0
Other revenues	115	72
Total revenues	15,010	15,572
Costs and expenses:
Cost of natural gas and NGLs	0	0
Operation and maintenance	2,451	1,672
General and administrative	2,098	1,647
Depreciation and amortization	3,384	3,173
Transaction costs	0
(Gain) loss on asset sales, net	0	0
Long-lived asset impairment		284
Total costs and expenses	7,933	6,776
Other (expense) income	0	0
Interest expense	0	0
Early extinguishment of debt		0
Deferred Purchase Price Obligation	0	0
(Loss) income before income taxes and income (loss) from equity method investees	7,077	8,796
Income tax benefit (expense)	0	0
Income (loss) from equity method investees	1,386	(656)
Equity in earnings of consolidated subsidiaries	0	0
Net loss	$ 8,463	$ 8,140