CONDENSED CONSOLIDATING FINANCIAL INFORMATION - Condensed Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 3,366		$ 1,430	$ 6,285	$ 7,428
Accounts receivable	68,811		72,301
Other current assets	3,535		4,327
Due from affiliate	0		0
Total current assets	75,712		78,058
Property, plant and equipment, net	1,858,312	$ 1,828,252	1,795,129
Intangible assets, net	293,771		301,345
Goodwill	16,211		16,211
Investment in equity method investees	682,227		690,485
Other noncurrent assets	13,153		13,565
Investment in subsidiaries	0		0
Total assets	2,939,386		2,894,793
Liabilities and Partners' Capital
Trade accounts payable	21,232		16,375
Accrued expenses	13,971		12,499
Due to affiliate	443		1,088
Deferred revenue	10,159	10,088	4,000
Ad valorem taxes payable	3,834		8,329
Accrued interest	15,383		12,310
Accrued environmental remediation	3,068		3,130
Other current liabilities	5,984		11,258
Total current liabilities	74,074		68,989
Long-term debt	1,091,602		1,051,192
Deferred Purchase Price Obligation	384,617		362,959
Noncurrent deferred revenue	36,587	$ 35,528	12,707
Noncurrent accrued environmental remediation	1,916		2,214
Other noncurrent liabilities	6,509		7,063
Total liabilities	1,595,305		1,505,124
Total partners' capital	1,344,081		1,389,669	1,125,115	1,169,673
Total liabilities and partners' capital	2,939,386		2,894,793
Consolidating adjustments
Assets
Cash and cash equivalents	0		0	0	0
Accounts receivable	0		0
Other current assets	0		0
Due from affiliate	(537,642)		(515,097)
Total current assets	(537,642)		(515,097)
Property, plant and equipment, net	0		0
Intangible assets, net	0		0
Goodwill	0		0
Investment in equity method investees	0		0
Other noncurrent assets	0		0
Investment in subsidiaries	(5,403,854)		(5,344,164)
Total assets	(5,941,496)		(5,859,261)
Liabilities and Partners' Capital
Trade accounts payable	0		0
Accrued expenses	0		0
Due to affiliate	(537,642)		(515,097)
Deferred revenue	0		0
Ad valorem taxes payable	0		0
Accrued interest	0		0
Accrued environmental remediation	0		0
Other current liabilities	0		0
Total current liabilities	(537,642)		(515,097)
Long-term debt	0		0
Deferred Purchase Price Obligation	0		0
Noncurrent deferred revenue	0		0
Noncurrent accrued environmental remediation	0		0
Other noncurrent liabilities	0		0
Total liabilities	(537,642)		(515,097)
Total partners' capital	(5,403,854)		(5,344,164)
Total liabilities and partners' capital	(5,941,496)		(5,859,261)
Summit Midstream Partners, LP | Reportable Legal Entities
Assets
Cash and cash equivalents	213		126	3,180	698
Accounts receivable	22		22
Other current assets	1,194		1,188
Due from affiliate	0		0
Total current assets	1,429		1,336
Property, plant and equipment, net	4,063		4,206
Intangible assets, net	0		0
Goodwill	0		0
Investment in equity method investees	0		0
Other noncurrent assets	2,768		2,547
Investment in subsidiaries	2,041,996		2,019,700
Total assets	2,050,256		2,027,789
Liabilities and Partners' Capital
Trade accounts payable	56		209
Accrued expenses	940		928
Due to affiliate	314,554		263,935
Deferred revenue	0		0
Ad valorem taxes payable	5		0
Accrued interest	0		0
Accrued environmental remediation	0		0
Other current liabilities	2,314		6,395
Total current liabilities	317,869		271,467
Long-term debt	0		0
Deferred Purchase Price Obligation	384,617		362,959
Noncurrent deferred revenue	0		0
Noncurrent accrued environmental remediation	0		0
Other noncurrent liabilities	3,689		3,694
Total liabilities	706,175		638,120
Total partners' capital	1,344,081		1,389,669
Total liabilities and partners' capital	2,050,256		2,027,789
Co-Issuers | Reportable Legal Entities
Assets
Cash and cash equivalents	368		75	5	51
Accounts receivable	0		0
Other current assets	0		0
Due from affiliate	0		0
Total current assets	368		75
Property, plant and equipment, net	0		0
Intangible assets, net	0		0
Goodwill	0		0
Investment in equity method investees	0		0
Other noncurrent assets	10,286		10,913
Investment in subsidiaries	3,361,858		3,324,464
Total assets	3,372,512		3,335,452
Liabilities and Partners' Capital
Trade accounts payable	0		0
Accrued expenses	0		0
Due to affiliate	223,531		252,250
Deferred revenue	0		0
Ad valorem taxes payable	0		0
Accrued interest	15,383		12,310
Accrued environmental remediation	0		0
Other current liabilities	0		0
Total current liabilities	238,914		264,560
Long-term debt	1,091,602		1,051,192
Deferred Purchase Price Obligation	0		0
Noncurrent deferred revenue	0		0
Noncurrent accrued environmental remediation	0		0
Other noncurrent liabilities	0		0
Total liabilities	1,330,516		1,315,752
Total partners' capital	2,041,996		2,019,700
Total liabilities and partners' capital	3,372,512		3,335,452
Guarantor Subsidiaries | Reportable Legal Entities
Assets
Cash and cash equivalents	2,331		1,138	2,784	5,768
Accounts receivable	60,378		65,842
Other current assets	1,955		2,697
Due from affiliate	500,061		493,067
Total current assets	564,725		562,744
Property, plant and equipment, net	1,504,830		1,442,333
Intangible assets, net	271,504		278,958
Goodwill	16,211		16,211
Investment in equity method investees	0		0
Other noncurrent assets	99		105
Investment in subsidiaries	0		0
Total assets	2,357,369		2,300,351
Liabilities and Partners' Capital
Trade accounts payable	16,822		11,283
Accrued expenses	11,607		10,592
Due to affiliate	0		0
Deferred revenue	9,722		4,000
Ad valorem taxes payable	3,693		7,809
Accrued interest	0		0
Accrued environmental remediation	0		0
Other current liabilities	3,338		4,385
Total current liabilities	45,182		38,069
Long-term debt	0		0
Deferred Purchase Price Obligation	0		0
Noncurrent deferred revenue	34,775		12,707
Noncurrent accrued environmental remediation	0		0
Other noncurrent liabilities	2,744		3,293
Total liabilities	82,701		54,069
Total partners' capital	2,274,668		2,246,282
Total liabilities and partners' capital	2,357,369		2,300,351
Non-Guarantor Subsidiaries | Reportable Legal Entities
Assets
Cash and cash equivalents	454		91	$ 316	$ 911
Accounts receivable	8,411		6,437
Other current assets	386		442
Due from affiliate	37,581		22,030
Total current assets	46,832		29,000
Property, plant and equipment, net	349,419		348,590
Intangible assets, net	22,267		22,387
Goodwill	0		0
Investment in equity method investees	682,227		690,485
Other noncurrent assets	0		0
Investment in subsidiaries	0		0
Total assets	1,100,745		1,090,462
Liabilities and Partners' Capital
Trade accounts payable	4,354		4,883
Accrued expenses	1,424		979
Due to affiliate	0		0
Deferred revenue	437		0
Ad valorem taxes payable	136		520
Accrued interest	0		0
Accrued environmental remediation	3,068		3,130
Other current liabilities	332		478
Total current liabilities	9,751		9,990
Long-term debt	0		0
Deferred Purchase Price Obligation	0		0
Noncurrent deferred revenue	1,812		0
Noncurrent accrued environmental remediation	1,916		2,214
Other noncurrent liabilities	76		76
Total liabilities	13,555		12,280
Total partners' capital	1,087,190		1,078,182
Total liabilities and partners' capital	$ 1,100,745		$ 1,090,462