CONDENSED CONSOLIDATING FINANCIAL INFORMATION - Condensed Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Total revenues	$ 127,479	$ 124,945	$ 372,982	$ 362,542
Costs and expenses:
Cost of natural gas and NGLs	$ 26,879	$ 18,177	$ 71,549	$ 36,328
Type of Cost, Good or Service [Extensible List]	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember
Operation and maintenance	$ 24,382	$ 22,303	$ 73,452	$ 70,011
General and administrative	11,740	13,289	39,666	40,370
Depreciation and amortization	26,743	28,927	80,204	86,184
Transaction costs	0	0	0	119
Loss (gain) on asset sales, net	6	460	(6)	530
Long-lived asset impairment	1,540	1,290	2,127	1,577
Total costs and expenses	91,290	84,446	266,992	235,119
Other income	58	79	78	214
Interest expense	(14,862)	(17,614)	(44,821)	(51,883)
Early extinguishment of debt	0	0	0	(22,020)
Deferred Purchase Price Obligation	37,204	70,499	(53,759)	54,674
Income before income taxes and (loss) income from equity method investees	58,589	93,463	7,488	108,408
Income tax benefit (expense)	35	(176)	(88)	(417)
(Loss) income from equity method investees	(1,169)	350	(3,703)	(3,691)
Equity in earnings of consolidated subsidiaries	0	0
Net income	57,455	93,637	$ 3,697	$ 104,300
Consolidating adjustments
Revenues:
Total revenues	0	0
Costs and expenses:
Cost of natural gas and NGLs	$ 0	$ 0
Type of Cost, Good or Service [Extensible List]	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember
Operation and maintenance	$ 0	$ 0
General and administrative	0	0
Depreciation and amortization	0	0
Loss (gain) on asset sales, net	0	0
Long-lived asset impairment	0	0
Total costs and expenses	0	0
Other income	0	0
Interest expense	0	0
Deferred Purchase Price Obligation	0	0
Income before income taxes and (loss) income from equity method investees	0	0
Income tax benefit (expense)	0	0
(Loss) income from equity method investees	0	0
Equity in earnings of consolidated subsidiaries	(56,036)	(64,788)	$ (162,363)	$ (175,119)
Net income	(56,036)	(64,788)	(162,363)	(175,119)
Gathering Services and Related Fees
Revenues:
Total revenues	86,427	96,070	260,373	298,884
Gathering Services and Related Fees | Consolidating adjustments
Revenues:
Total revenues	0	0
Natural Gas, NGLs and Condensate Sales
Revenues:
Total revenues	34,017	22,940	92,025	44,655
Natural Gas, NGLs and Condensate Sales | Consolidating adjustments
Revenues:
Total revenues	0	0
Other Revenues
Revenues:
Total revenues	7,035	5,935	$ 20,584	$ 19,003
Other Revenues | Consolidating adjustments
Revenues:
Total revenues	0	0
Summit Midstream Partners, LP | Reportable Legal Entities
Revenues:
Total revenues	0	0
Costs and expenses:
Cost of natural gas and NGLs	$ 0	$ 0
Type of Cost, Good or Service [Extensible List]	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember
Operation and maintenance	$ 0	$ 0
General and administrative	0	0
Depreciation and amortization	429	352	$ 1,305	$ 660
Transaction costs				119
Loss (gain) on asset sales, net	0	0
Long-lived asset impairment	0	0
Total costs and expenses	429	352	1,305	779
Other income	58	79	78	214
Interest expense	0	0
Deferred Purchase Price Obligation	37,204	70,499	(53,759)	54,674
Income before income taxes and (loss) income from equity method investees	36,833	70,226	(54,986)	54,109
Income tax benefit (expense)	35	(176)	(88)	(417)
(Loss) income from equity method investees	0	0
Equity in earnings of consolidated subsidiaries	20,587	23,587	58,771	50,608
Net income	57,455	93,637	$ 3,697	$ 104,300
Summit Midstream Partners, LP | Gathering Services and Related Fees | Reportable Legal Entities
Revenues:
Total revenues	0	0
Summit Midstream Partners, LP | Natural Gas, NGLs and Condensate Sales | Reportable Legal Entities
Revenues:
Total revenues	0	0
Summit Midstream Partners, LP | Other Revenues | Reportable Legal Entities
Revenues:
Total revenues	0	0
Co-Issuers | Reportable Legal Entities
Revenues:
Total revenues	0	0
Costs and expenses:
Cost of natural gas and NGLs	$ 0	$ 0
Type of Cost, Good or Service [Extensible List]	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember
Operation and maintenance	$ 0	$ 0
General and administrative	0	0
Depreciation and amortization	0	0
Loss (gain) on asset sales, net	0	0
Long-lived asset impairment	0	0
Total costs and expenses	0	0
Other income	0	0
Interest expense	(14,862)	(17,614)	$ (44,821)	$ (51,883)
Early extinguishment of debt				(22,020)
Deferred Purchase Price Obligation	0	0
Income before income taxes and (loss) income from equity method investees	(14,862)	(17,614)	(44,821)	(73,903)
Income tax benefit (expense)	0	0
(Loss) income from equity method investees	0	0
Equity in earnings of consolidated subsidiaries	35,449	41,201	103,592	124,511
Net income	20,587	23,587	58,771	50,608
Co-Issuers | Gathering Services and Related Fees | Reportable Legal Entities
Revenues:
Total revenues	0	0
Co-Issuers | Natural Gas, NGLs and Condensate Sales | Reportable Legal Entities
Revenues:
Total revenues	0	0
Co-Issuers | Other Revenues | Reportable Legal Entities
Revenues:
Total revenues	0	0
Guarantor Subsidiaries | Reportable Legal Entities
Revenues:
Total revenues	113,837	110,969	328,438	315,808
Costs and expenses:
Cost of natural gas and NGLs	$ 26,879	$ 18,177	$ 71,549	$ 36,328
Type of Cost, Good or Service [Extensible List]	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember
Operation and maintenance	$ 21,721	$ 20,217	$ 66,095	$ 64,405
General and administrative	10,535	11,919	34,786	35,283
Depreciation and amortization	22,863	25,247	68,500	75,772
Loss (gain) on asset sales, net	1	(82)	(74)	(11)
Long-lived asset impairment	275	696	862	698
Total costs and expenses	82,274	76,174	241,718	212,475
Other income	0	0
Interest expense	0	0
Deferred Purchase Price Obligation	0	0
Income before income taxes and (loss) income from equity method investees	31,563	34,795	86,720	103,333
Income tax benefit (expense)	0	0
(Loss) income from equity method investees	0	0
Equity in earnings of consolidated subsidiaries	0	0
Net income	31,563	34,795	86,720	103,333
Guarantor Subsidiaries | Gathering Services and Related Fees | Reportable Legal Entities
Revenues:
Total revenues	73,014	82,152	216,371	252,344
Guarantor Subsidiaries | Natural Gas, NGLs and Condensate Sales | Reportable Legal Entities
Revenues:
Total revenues	34,017	22,940	92,025	44,655
Guarantor Subsidiaries | Other Revenues | Reportable Legal Entities
Revenues:
Total revenues	6,806	5,877	20,042	18,809
Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenues:
Total revenues	13,642	13,976	$ 44,544	$ 46,734
Costs and expenses:
Cost of natural gas and NGLs	$ 0	$ 0
Type of Cost, Good or Service [Extensible List]	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember
Operation and maintenance	$ 2,661	$ 2,086	$ 7,357	$ 5,606
General and administrative	1,205	1,370	4,880	5,087
Depreciation and amortization	3,451	3,328	10,399	9,752
Loss (gain) on asset sales, net	5	542	68	541
Long-lived asset impairment	1,265	594	1,265	879
Total costs and expenses	8,587	7,920	23,969	21,865
Other income	0	0
Interest expense	0	0
Deferred Purchase Price Obligation	0	0
Income before income taxes and (loss) income from equity method investees	5,055	6,056	20,575	24,869
Income tax benefit (expense)	0	0
(Loss) income from equity method investees	(1,169)	350	(3,703)	(3,691)
Equity in earnings of consolidated subsidiaries	0	0
Net income	3,886	6,406	16,872	21,178
Non-Guarantor Subsidiaries | Gathering Services and Related Fees | Reportable Legal Entities
Revenues:
Total revenues	13,413	13,918	44,002	46,540
Non-Guarantor Subsidiaries | Natural Gas, NGLs and Condensate Sales | Reportable Legal Entities
Revenues:
Total revenues	0	0
Non-Guarantor Subsidiaries | Other Revenues | Reportable Legal Entities
Revenues:
Total revenues	$ 229	$ 58	$ 542	$ 194