Summit Midstream Partners (SMLP) 10-Q 3 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Entity Information [Line Items]
Entity Registrant Name	Summit Midstream Partners, LP
Entity Central Index Key	1,549,922
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Trading Symbol	SMLP
Common units
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		73,060,122
General Partner Units
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		1,490,999

UNAUDITED CONDENSED CONSOLIDATE

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 2,911	$ 7,428
Accounts receivable	61,267	97,364
Other current assets	4,785	4,309
Total current assets	68,963	109,101
Property, plant and equipment, net	1,884,569	1,853,671
Intangible assets, net	392,035	421,452
Goodwill	16,211	16,211
Investment in equity method investees	696,590	707,415
Other noncurrent assets	13,753	7,329
Total assets	3,072,121	3,115,179
Current liabilities:
Trade accounts payable	22,676	16,251
Accrued expenses	14,115	11,389
Due to affiliate	514	258
Deferred revenue	2,373	0
Ad valorem taxes payable	8,118	10,588
Accrued interest	20,183	17,483
Accrued environmental remediation	5,089	4,301
Other current liabilities	8,963	11,471
Total current liabilities	82,031	71,741
Long-term debt	1,295,787	1,240,301
Deferred Purchase Price Obligation	508,607	563,281
Deferred revenue	15,421	57,465
Noncurrent accrued environmental remediation	1,429	5,152
Other noncurrent liabilities	7,538	7,566
Total liabilities	1,910,813	1,945,506
Commitments and contingencies (Note 15)
Common limited partner capital (73,059 units issued and outstanding at September 30, 2017 and 72,111 units issued and outstanding at December 31, 2016)	1,120,592	1,129,132
General Partner interests (1,491 units issued and outstanding at September 30, 2017 and 1,471 units issued and outstanding at December 31, 2016)	29,187	29,294
Noncontrolling interest	11,529	11,247
Total partners' capital	1,161,308	1,169,673
Total liabilities and partners' capital	$ 3,072,121	$ 3,115,179

UNAUDITED CONDENSED CONSOLIDAT3

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares shares in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Common limited partner capital (shares)	73,059	72,111
Common limited partner capital (shares)	73,059	72,111
General partner interests (shares)	1,491	1,471
General partner interests (shares)	1,491	1,471

UNAUDITED CONDENSED CONSOLIDAT4

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Gathering services and related fees	$ 96,070	$ 80,296	$ 298,884	$ 234,583
Natural gas, NGLs and condensate sales	22,940	9,578	44,655	25,747
Other revenues	5,935	5,199	19,003	14,949
Total revenues	124,945	95,073	362,542	275,279
Costs and expenses:
Cost of natural gas and NGLs	18,177	6,986	36,328	20,140
Operation and maintenance	22,303	23,059	70,011	72,311
General and administrative	13,289	12,368	40,370	38,123
Depreciation and amortization	28,927	27,979	86,184	83,670
Transaction costs	0	0	119	1,296
Loss on asset sales, net	460	13	530	24
Long-lived asset impairment	1,290	1,172	1,577	1,741
Total costs and expenses	84,446	71,577	235,119	217,305
Other income	79	51	214	92
Interest expense	(17,614)	(15,733)	(51,883)	(47,650)
Early extinguishment of debt	0	0	(22,020)	0
Deferred Purchase Price Obligation	70,499	(6,188)	54,674	(31,116)
Income (loss) before income taxes and income (loss) from equity method investees	93,463	1,626	108,408	(20,700)
Income tax (expense) benefit	(176)	142	(417)	(141)
Income (loss) from equity method investees	350	270	(3,691)	(31,341)
Net income (loss)	93,637	2,038	104,300	(52,182)
Net income attributable to Summit Investments	0	0	0	2,745
Net income (loss) attributable to noncontrolling interest	91	116	282	(108)
Net income (loss) attributable to SMLP	93,546	1,922	104,018	(54,819)
Less net income attributable to General Partner, including IDRs	3,999	2,137	8,442	4,883
Net income (loss) attributable to limited partners	$ 89,547	$ (215)	$ 95,576	$ (59,702)
Common units
Earnings (loss) per limited partner unit:
Common unit – basic	$ 1.23	$ 0	$ 1.32	$ (0.89)
Common unit – diluted	$ 1.22	$ 0	$ 1.31	$ (0.89)
Weighted-average limited partner units outstanding:
Common units – basic	73,059	67,844	72,583	66,978
Common units – diluted	73,433	67,844	72,901	66,978

UNAUDITED CONDENSED CONSOLIDAT5

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF PARTNERS' CAPITAL - USD ($) $ in Thousands	Total	Class B membership interest	Noncontrolling interest	Summit Investments' equity in contributed subsidiaries	Summit Investments' equity in contributed subsidiariesClass B membership interest	Limited partners, Common	Limited partners, CommonClass B membership interest	Limited partners, Subordinated	General Partner
Beginning balance at Dec. 31, 2015	$ 1,747,299		$ 0	$ 763,057		$ 744,977		$ 213,631	$ 25,634
Net (loss) income	(52,182)		(108)	2,745		(60,742)		1,040	4,883
Distributions to unitholders	(123,064)					(100,762)		(14,034)	(8,268)
Unit-based compensation	5,625	$ 375			$ 130	5,625	$ 245
Tax withholdings on vested SMLP LTIP awards	(796)					(796)
Issuance of common units, net of offering costs	126,115					126,115
Contribution from General Partner	2,702								2,702
Subordinated units conversion						200,637		(200,637)
Purchase of 2016 Drop Down Assets	(866,858)			(866,858)
Establishment of noncontrolling interest			11,261	(11,261)
Distribution of debt related to Carve-Out Financial Statements of Summit Investments	342,926			342,926
Excess of acquired carrying value over consideration paid for 2016 Drop Down Assets	247,997			(247,997)		243,044			4,953
Cash advance from Summit Investments to contributed subsidiaries, net	12,214			12,214
Expenses paid by Summit Investments on behalf of contributed subsidiaries	4,821			4,821
Capitalized interest allocated from Summit Investments to contributed subsidiaries	223			223
Ending balance at Sep. 30, 2016	1,199,400		11,153	$ 0		1,158,343		$ 0	29,904
Beginning balance at Dec. 31, 2016	1,169,673		11,247			1,129,132			29,294
Net (loss) income	104,300		282			95,576			8,442
Distributions to unitholders	(134,066)		0			(125,052)			(9,014)
Unit-based compensation	5,902		0			5,902			0
Tax withholdings on vested SMLP LTIP awards	(2,051)		0			(2,051)			0
Issuance of common units, net of offering costs	17,251		0			17,251			0
Contribution from General Partner	465		0			0			465
Distribution of debt related to Carve-Out Financial Statements of Summit Investments	0
Excess of acquired carrying value over consideration paid for 2016 Drop Down Assets	0
Capitalized interest allocated from Summit Investments to contributed subsidiaries	0
Other	(166)		0			(166)			0
Ending balance at Sep. 30, 2017	$ 1,161,308		$ 11,529			$ 1,120,592			$ 29,187

UNAUDITED CONDENSED CONSOLIDAT6

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net (loss) income	$ 104,300	$ (52,182)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	85,732	84,058
Amortization of debt issuance costs	3,117	3,027
Deferred Purchase Price Obligation	(54,674)	31,116
Unit-based and noncash compensation	5,973	6,000
Loss from equity method investees	3,691	31,341
Distributions from equity method investees	28,715	34,139
Loss on asset sales, net	530	24
Long-lived asset impairment	1,577	1,741
Early extinguishment of debt	22,020	0
Write-off of debt issuance costs	302	0
Changes in operating assets and liabilities:
Accounts receivable	36,097	37,133
Trade accounts payable	1,200	(1,795)
Accrued expenses	2,726	3,440
Due from (to) affiliate	256	(1,035)
Deferred revenue	(39,671)	2,879
Ad valorem taxes payable	(2,470)	(858)
Accrued interest	2,700	(9,750)
Accrued environmental remediation, net	(2,935)	(2,628)
Other, net	(2,689)	2,055
Net cash provided by operating activities	196,497	168,705
Cash flows from investing activities:
Capital expenditures	(86,206)	(122,735)
Proceeds from asset sale	2,300	0
Contributions to equity method investees	(21,581)	(20,157)
Acquisitions of gathering systems from affiliate	0	(359,431)
Other, net	(579)	(373)
Net cash provided by (used in) investing activities	(106,066)	(502,696)
Cash flows from financing activities:
Distributions to unitholders	(134,066)	(123,064)
Borrowings under Revolving Credit Facility	177,500	490,300
Repayments under Revolving Credit Facility	(319,500)	(189,300)
Debt issuance costs	(15,891)	(3,013)
Payment of redemption and call premiums on senior notes	(17,913)	0
Proceeds from ATM Program issuances, net of costs	17,251	0
Proceeds from issuance of common units, net	0	126,115
Contribution from General Partner	465	2,702
Cash advance from Summit Investments to contributed subsidiaries, net	0	12,214
Expenses paid by Summit Investments on behalf of contributed subsidiaries	0	4,821
Issuance of senior notes	500,000	0
Tender and redemption of senior notes	(300,000)	0
Other, net	(2,794)	(980)
Advances from affiliates	0	0
Net cash provided by (used in) financing activities	(94,948)	319,795
Net change in cash and cash equivalents	(4,517)	(14,196)
Cash and cash equivalents, beginning of period	7,428	21,793
Cash and cash equivalents, end of period	2,911	7,597
Supplemental cash flow disclosures:
Cash interest paid	47,410	57,217
Less capitalized interest	1,562	3,133
Interest paid (net of capitalized interest)	45,848	54,084
Noncash investing and financing activities
Capital expenditures in trade accounts payable (period end accruals)	13,647	9,076
Issuance of Deferred Purchase Price Obligation to affiliate to partially fund the 2016 Drop Down	0	507,427
Excess of acquired carrying value over consideration paid for 2016 Drop Down Assets	0	247,997
Distribution of debt related to Carve-Out Financial Statements of Summit Investments	0	342,926
Capitalized interest allocated from Summit Investments to contributed subsidiaries	$ 0	$ 223

ORGANIZATION, BUSINESS OPERATIO

ORGANIZATION, BUSINESS OPERATIONS AND PRESENTATION AND CONSOLIDATION	9 Months Ended
	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
ORGANIZATION, BUSINESS OPERATIONS AND PRESENTATION AND CONSOLIDATION	1. ORGANIZATION, BUSINESS OPERATIONS AND PRESENTATION AND CONSOLIDATION Organization. SMLP, a Delaware limited partnership, was formed in May 2012 and began operations in October 2012 in connection with its IPO of common limited partner units. SMLP is a growth-oriented limited partnership focused on developing, owning and operating midstream energy infrastructure assets that are strategically located in the core producing areas of unconventional resource basins, primarily shale formations, in the continental United States. Our business activities are conducted through various operating subsidiaries, each of which is owned or controlled by our wholly owned subsidiary holding company, Summit Holdings, a Delaware limited liability company. References to the "Partnership," "we," or "our" refer collectively to SMLP and its subsidiaries. The General Partner, a Delaware limited liability company, manages our operations and activities. Summit Investments, a Delaware limited liability company, is the ultimate owner of our General Partner and has the right to appoint the entire Board of Directors. Summit Investments is controlled by Energy Capital Partners. As of September 30, 2017, a subsidiary of Energy Capital Partners directly owned In addition to its approximate Neither SMLP nor its subsidiaries have any employees. All of the personnel that conduct our business are employed by Summit Investments, but these individuals are sometimes referred to as our employees. Business Operations. We provide natural gas gathering, treating and processing services as well as crude oil and produced water gathering services pursuant to primarily long-term and fee-based agreements with our customers. Our results are driven primarily by the volumes of natural gas that we gather, treat, compress and process as well as by the volumes of crude oil and produced water that we gather. We are the owner-operator of or have significant ownership interests in the following gathering systems: • Ohio Gathering, a natural gas gathering system and a condensate stabilization facility operating in the Appalachian Basin, which includes the Utica and Point Pleasant shale formations in southeastern Ohio; • Summit Utica, a natural gas gathering system operating in the Appalachian Basin, which includes the Utica and Point Pleasant shale formations in southeastern Ohio; • Bison Midstream, an associated natural gas gathering system operating in the Williston Basin, which includes the Bakken and Three Forks shale formations in northwestern North Dakota; • Polar and Divide, crude oil and produced water gathering systems and transmission pipelines located in the Williston Basin, which includes the Bakken and Three Forks shale formations in northwestern North Dakota; • Tioga Midstream, crude oil, produced water and associated natural gas gathering systems operating in the Williston Basin, which includes the Bakken and Three Forks shale formations in northwestern North Dakota; • Grand River, a natural gas gathering and processing system located in the Piceance Basin, which includes the Mesaverde formation and the Mancos and Niobrara shale formations in western Colorado and eastern Utah; • Niobrara G&P, an associated natural gas gathering and processing system operating in the DJ Basin, which includes the Niobrara and Codell shale formations in northeastern Colorado; • DFW Midstream, a natural gas gathering system operating in the Fort Worth Basin, which includes the Barnett Shale formation in north-central Texas; • Mountaineer Midstream, a natural gas gathering system operating in the Appalachian Basin, which includes the Marcellus Shale formation in northern West Virginia; and • Summit Permian, an associated natural gas gathering and processing system under development in the northern Delaware Basin in southeastern New Mexico. In February 2016, the Partnership and SMP Holdings, a wholly owned subsidiary of Summit Investments, entered into a contribution agreement (the "Contribution Agreement") pursuant to which SMP Holdings agreed to contribute to the Partnership substantially all of its limited partner interest in OpCo, a Delaware limited partnership that owns (i) Summit Marketing (formerly known as Summit Midstream OpCo GP, LLC), a Delaware limited liability company and a wholly owned subsidiary of Summit Holdings, manages OpCo, a Delaware limited liability partnership, and provides natural gas and crude oil marketing services in and around our gathering systems. Presentation and Consolidation. We prepare our unaudited condensed consolidated financial statements in accordance with GAAP as established by the FASB. We make estimates and assumptions that affect the reported amounts of assets and liabilities at the balance sheet dates, including fair value measurements, the reported amounts of revenue and expense and the disclosure of contingencies. Although management believes these estimates are reasonable, actual results could differ from its estimates. The unaudited condensed consolidated financial statements include the assets, liabilities and results of operations of SMLP and its subsidiaries. All intercompany transactions among the consolidated entities have been eliminated in consolidation. Comprehensive income or loss is the same as net income or loss for all periods presented. The financial position, results of operations and cash flows of acquired drop down assets, liabilities, expenses or entities that were carved out of entities held by Summit Investments and included herein have been derived from the accounting records of the respective Summit Investments' subsidiary on a carve-out basis. SMLP recognized its drop down acquisitions at Summit Investments' historical cost because the acquisitions were executed by entities under common control. The excess of Summit Investments' net investment over the consideration paid and recognized for a contributed subsidiary is recognized as an addition to partners' capital, while the excess of purchase price paid and recognized over net investment is recognized as a reduction to partners' capital. Due to the common control aspect, we account for drop down transactions on an “as-if pooled” basis for the periods during which common control existed. These unaudited condensed consolidated financial statements have been prepared pursuant to the rules and the regulations of the SEC. Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations. We believe that the disclosures made are adequate to make the information not misleading. In the opinion of management, the unaudited condensed consolidated financial statements contain all adjustments, including normal recurring adjustments, which are necessary to fairly present the unaudited condensed consolidated balance sheet as of September 30, 2017, the unaudited condensed consolidated statements of operations for the three and nine month periods ended September 30, 2017 and 2016 and the unaudited condensed consolidated statements of partners' capital and cash flows for the nine month periods ended September 30, 2017 and 2016. The balance sheet at December 31, 2016 included herein was derived from our audited financial statements, but does not include all disclosures required by GAAP. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto that are included in our annual report on Form 10-K for the year ended December 31, 2016, as filed with the SEC on February 27, 2017 (the "2016 Annual Report"). The results of operations for an interim period are not necessarily indicative of results expected for a full year.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES There have been no changes to our significant accounting policies since December 31, 2016. Recent Accounting Pronouncements. Accounting standard setters frequently issue new or revised accounting rules. We review new pronouncements to determine the impact, if any, on our financial statements. Accounting standards that have or could possibly have a material effect on our financial statements are discussed below. Recently Adopted Accounting Pronouncements • ASU No. 2016-09 Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting ("ASU 2016-09"). ASU 2016-09 simplifies several aspects for share-based payment award transactions, including income tax consequences, the liability or equity classification of awards and classification on the statements of cash flows. ASU 2016-09 is effective for public companies for fiscal years beginning after December 15, 2016. It does not specify a single transition approach, rather it specifies retrospective, modified retrospective and/or prospective transition approaches based on the aspect being applied. We adopted the provisions of ASU 2016-09 effective January 1, 2017. The adoption of this standard had no impact on our consolidated financial statements. Accounting Pronouncements Pending Adoption • ASU No. 2014-09 Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"). Under ASU 2014-09, revenue will be recognized under a five-step model: (i) identify the contract with the customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to performance obligations; and (v) recognize revenue when (or as) the performance obligation is satisfied. ASU 2014-09 is effective for fiscal years and interim periods within those years, beginning after December 15, 2017 and allows for early adoption. We expect to adopt the provisions of ASU 2014-09 effective January 1, 2018 using the modified retrospective method. We have completed reviewing our existing contract portfolio in place as of September 30, 2017 under ASU 2014-09 and have quantified the expected impact of adoption. For contracts where we perform gathering services and earn a per-unit fee which is recognized at a point in time, revenue will be recognized over time as the service is performed and will result in revenue recognition materially consistent with current GAAP. In addition, our contracts generally contain forms of what will be considered variable consideration, which will likely be constrained as the volumes are susceptible to factors outside of our control and influence. As a result of applying the constraint guidance, timing of revenue recognition will be materially consistent with current GAAP. However, we will be billing amounts that correspond directly to the value transferred such that the resulting revenue recognized will be consistent with current GAAP. Contributions in aid of construction received prior to adoption were recognized as a reduction to property, plant and equipment. Upon adoption of the new guidance, those amounts will be capitalized to property, plant and equipment, net of any accumulated depreciation, and depreciated over the remaining useful lives. Going forward, any contributions in aid of construction will be recognized as revenue over the remaining term of the respective contract in accordance with ASU 2014-09. The cumulative expected impact upon adoption for contributions in aid of construction is anticipated to be a net increase in property, plant and equipment of between $30.0 and $33.0 million, a net increase in partners’ capital of between $8.0 and $10.0 million and an increase in deferred revenue of between $22.0 and $25.0 million. The cumulative expected impact upon adoption for facility fees will be a decrease in partners’ capital of between $11.0 and $13.0 million and an increase in deferred revenue of between $11.0 and $13.0 million. We are continuing to work with our midstream industry peers to develop our position on certain implementation matters including the presentation and disclosure of percent-of-proceeds contracts. We will finalize our assessment of the adoption of ASU 2014-09 and will disclose any further updates along with the practical expedients we expect to utilize in our Form 10-K for the year ended December 31, 2017. • ASU No. 2016-02 Leases (Topic 842) ("ASU 2016-02"). ASU 2016-02 requires that lessees recognize all leases on the balance sheet, with the exception of short-term leases. A lease liability will be recorded for the obligation of a lessee to make lease payments arising from a lease. A right-of-use asset will be recorded which represents the lessee’s right to use, or to control the use of, a specified asset for a lease term. We are currently evaluating the impact of this guidance on lessor accounting but have made no determinations at this time. ASU 2016-02 is effective for public companies for fiscal years beginning after December 15, 2018, and requires the modified retrospective approach for transition. We are currently evaluating the provisions of ASU 2016-02 to determine its impact on our financial statements and related disclosures and expect to adopt its provisions effective January 1, 2019. • ASU No. 2016-08 Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net) ("ASU 2016-08"). ASU 2016-08 does not change the core principle of Topic 606, rather it clarifies the implementation guidance on principal versus agent considerations. We expect to adopt the provisions of ASU 2016-08 effective January 1, 2018. Our position regarding the impact of and transition method for this update is the same as for ASU 2014-09. • ASU No. 2016-10 Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing ("ASU 2016-10"). ASU 2016-10 clarifies the following two aspects of Topic 606: (i) identifying performance obligations; and (ii) the licensing implementation guidance, while retaining the related principles for those areas. We expect to adopt the provisions of ASU 2016-10 effective January 1, 2018. Our position regarding the impact of and transition method for this update is the same as for ASU 2014-09. • ASU No. 2016-12 Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients ("ASU 2016-12"). ASU 2016-12 does not change the core principle of the guidance in Topic 606. Rather, the amendments therein affect only the narrow aspects of Topic 606 including assessing the collectability criterion and issues related to contract modification at transition and completed contracts at transition. We expect to adopt the provisions of ASU 2016-12 effective January 1, 2018. Our position regarding the impact of and transition method for this update is the same as for ASU 2014-09.

SEGMENT INFORMATION

SEGMENT INFORMATION	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
SEGMENT INFORMATION	3. SEGMENT INFORMATION We evaluate our business operations each reporting period to determine whether any of our gathering system operating segments in which we internally report financial information are considered significant and would require us to separately disclose certain segment financial information in our external reporting. As a result of our evaluation during the second quarter of 2017, we determined that both the Summit Utica natural gas gathering system and the Ohio Gathering natural gas gathering system, each previously reported within the Utica Shale reportable segment, were and are expected to continue to be significant operating segments. As such, we modified our current segments in the second quarter of 2017 such that the Utica Shale reportable segment includes the Summit Utica gathering system and the Ohio Gathering reportable segment includes our ownership interest in OGC and OCC. For the three and nine months ended September 30, 2017, we have disclosed the required segment information for Summit Utica and Ohio Gathering and the periods prior to January 1, 2017 have been recast to reflect this change. As of September 30, 2017, our reportable segments are: • the Utica Shale, which is served by Summit Utica; • Ohio Gathering, which includes our ownership interest in OGC and OCC; • the Williston Basin, which is served by Bison Midstream, Polar and Divide and Tioga Midstream; • the Piceance/DJ Basins, which is served by Grand River and Niobrara G&P; • the Barnett Shale, which is served by DFW Midstream; and • the Marcellus Shale, which is served by Mountaineer Midstream. Each of our reportable segments provides midstream services in a specific geographic area. Our reportable segments reflect the way in which we internally report the financial information used to make decisions and allocate resources in connection with our operations. As noted above, the Ohio Gathering reportable segment includes our investment in Ohio Gathering (see Note 7). Income or loss from equity method investees, as reflected on the statements of operations, solely relates to Ohio Gathering and is recognized and disclosed on a one-month lag (see Note 7). No other line items in the statements of operations or cash flows, as disclosed in the tables below, include results for our investment in Ohio Gathering. Corporate and other represents those results that are: (i) not specifically attributable to a reportable segment; (ii) not individually reportable; or (iii) that have not been allocated to our reportable segments for the purpose of evaluating their performance, including certain general and administrative expense items, natural gas and crude oil marketing services, and transaction costs. Assets by reportable segment follow. September 30, 2017 December 31, 2016 (In thousands) Assets: Utica Shale $ 212,339 $ 199,392 Ohio Gathering 696,590 707,415 Williston Basin 695,120 724,084 Piceance/DJ Basins 799,410 843,440 Barnett Shale 389,026 404,314 Marcellus Shale 219,909 224,709 Total reportable segment assets 3,012,394 3,103,354 Corporate and other 60,699 12,294 Eliminations (972 ) (469 ) Total assets $ 3,072,121 $ 3,115,179 Revenues by reportable segment follow. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Revenues (1): Utica Shale $ 9,727 $ 7,665 $ 28,979 $ 17,351 Williston Basin 27,821 30,194 123,820 87,710 Piceance/DJ Basins 53,875 31,076 122,446 89,479 Barnett Shale 16,694 19,490 55,340 60,747 Marcellus Shale 8,160 6,648 22,429 19,992 Total reportable segments revenue 116,277 95,073 353,014 275,279 Corporate and other 11,816 — 14,964 — Eliminations (3,148 ) — (5,436 ) — Total revenues $ 124,945 $ 95,073 $ 362,542 $ 275,279 (1) Excludes revenues earned by Ohio Gathering due to equity method accounting. Counterparties accounting for more than 10% of total revenues were as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Percentage of total revenues (1)(2): Counterparty A - Piceance/DJ Basins 17 % * * * Counterparty B - Williston Basin * * 16 % * Counterparty C - Piceance/DJ Basins * 10 % * * (1) Includes recognition of revenue that was previously deferred in connection with minimum volume commitments (see Note 8). (2) Excludes revenues earned by Ohio Gathering due to equity method accounting. * Less than 10% Depreciation and amortization, including the amortization expense associated with our favorable and unfavorable gas gathering contracts as reported in other revenues, by reportable segment follows. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Depreciation and amortization (1): Utica Shale $ 1,818 $ 961 $ 5,213 $ 2,756 Williston Basin 8,405 8,446 25,171 25,214 Piceance/DJ Basins 12,199 12,273 36,635 36,843 Barnett Shale (2) 3,735 4,043 11,259 12,155 Marcellus Shale 2,268 2,224 6,794 6,665 Total reportable segment depreciation and amortization 28,425 27,947 85,072 83,633 Corporate and other 352 154 660 425 Total depreciation and amortization $ 28,777 $ 28,101 $ 85,732 $ 84,058 (1) Excludes depreciation and amortization recognized by Ohio Gathering due to equity method accounting. (2) Includes the amortization expense associated with our favorable and unfavorable gas gathering contracts as reported in other revenues. Cash paid for capital expenditures by reportable segment follow. Nine months ended September 30, 2017 2016 (In thousands) Cash paid for capital expenditures (1): Utica Shale $ 21,425 $ 72,036 Williston Basin 13,735 30,687 Piceance/DJ Basins 17,902 15,421 Barnett Shale 119 2,716 Marcellus Shale 628 971 Total reportable segment capital expenditures 53,809 121,831 Corporate and other 32,397 904 Total cash paid for capital expenditures $ 86,206 $ 122,735 (1) Excludes cash paid for capital expenditures by Ohio Gathering due to equity method accounting. During the nine months ended September 30, 2017, Corporate and other primarily includes cash paid for capital expenditures of approximately We assess the performance of our reportable segments based on segment adjusted EBITDA. For the purpose of evaluating segment performance, we exclude the effect of Corporate and other revenues and expenses, such as certain general and administrative expenses (including compensation-related expenses and professional services fees), natural gas and crude oil marketing services, transaction costs, interest expense, change in the Deferred Purchase Price Obligation fair value, early extinguishment of debt expense and income tax expense or benefit from segment adjusted EBITDA. Segment adjusted EBITDA by reportable segment follows. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Reportable segment adjusted EBITDA Utica Shale $ 8,412 $ 6,983 $ 25,857 $ 14,898 Ohio Gathering 10,522 10,059 29,201 35,173 Williston Basin 16,212 21,815 51,176 60,745 Piceance/DJ Basins 30,008 28,074 86,256 79,120 Barnett Shale 10,838 13,128 35,924 41,118 Marcellus Shale 6,682 5,146 17,775 14,554 Total of reportable segments' measures of profit or loss $ 82,674 $ 85,205 $ 246,189 $ 245,608 A reconciliation of income or loss before income taxes and loss from equity method investees to total of reportable segments' measures of profit or loss follows. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Reconciliation of income or loss before income taxes and income or loss from equity method investees to total of reportable segments' measures of profit or loss: Income (loss) before income taxes and income (loss) from equity method investees $ 93,463 $ 1,626 $ 108,408 $ (20,700 ) Add: Corporate and other 9,197 8,722 28,725 26,728 Interest expense 17,614 15,733 51,883 47,650 Early extinguishment of debt — — 22,020 — Deferred Purchase Price Obligation (70,499 ) 6,188 (54,674 ) 31,116 Depreciation and amortization 28,777 28,101 85,732 84,058 Proportional adjusted EBITDA for equity method investees 10,522 10,059 29,201 35,173 Adjustments related to MVC shortfall payments (10,124 ) 11,541 (33,186 ) 33,818 Unit-based and noncash compensation 1,974 2,050 5,973 6,000 Loss on asset sales, net 460 13 530 24 Long-lived asset impairment 1,290 1,172 1,577 1,741 Total of reportable segments' measures of profit or loss $ 82,674 $ 85,205 $ 246,189 $ 245,608 We include adjustments related to MVC shortfall payments in our calculation of segment adjusted EBITDA to account for (i) the net increases or decreases in deferred revenue for MVC shortfall payments and (ii) our inclusion of expected annual MVC shortfall payments. With respect to the impact of a net change in deferred revenue for MVC shortfall payments, we treat increases in deferred revenue balances as a favorable adjustment to segment adjusted EBITDA, while decreases in deferred revenue balances are treated as an unfavorable adjustment to segment adjusted EBITDA. We also include a proportional amount of any historical and expected MVC shortfall payments in each quarter prior to the quarter in which we actually recognize the shortfall payment. The expected MVC shortfall payment adjustments have not been billed to our customers and are not recognized in our unaudited condensed consolidated financial statements. Adjustments related to MVC shortfall payments by reportable segment follow. Three months ended September 30, 2017 Williston Basin Piceance/DJ Basins Barnett Shale Total (In thousands) Adjustments related to MVC shortfall payments: Net change in deferred revenue for MVC shortfall payments $ — $ — $ — $ — Expected MVC shortfall adjustments 1,982 (12,200 ) 94 (10,124 ) Total adjustments related to MVC shortfall payments $ 1,982 $ (12,200 ) $ 94 $ (10,124 ) Three months ended September 30, 2016 Williston Basin Piceance/DJ Basins Barnett Shale Total (In thousands) Adjustments related to MVC shortfall payments: Net change in deferred revenue for MVC shortfall payments $ — $ 847 $ — $ 847 Expected MVC shortfall adjustments 4,195 6,412 87 10,694 Total adjustments related to MVC shortfall payments $ 4,195 $ 7,259 $ 87 $ 11,541 Nine months ended September 30, 2017 Williston Basin Piceance/DJ Basins Barnett Shale Total (In thousands) Adjustments related to MVC shortfall payments: Net change in deferred revenue for MVC shortfall payments $ (37,693 ) $ (1,978 ) $ — $ (39,671 ) Expected MVC shortfall adjustments 5,946 867 (328 ) 6,485 Total adjustments related to MVC shortfall payments $ (31,747 ) $ (1,111 ) $ (328 ) $ (33,186 ) Nine months ended September 30, 2016 Williston Basin Piceance/DJ Basins Barnett Shale Total (In thousands) Adjustments related to MVC shortfall payments: Net change in deferred revenue for MVC shortfall payments $ 235 $ 3,321 $ (677 ) $ 2,879 Expected MVC shortfall adjustments 11,757 18,911 271 30,939 Total adjustments related to MVC shortfall payments $ 11,992 $ 22,232 $ (406 ) $ 33,818

PROPERTY, PLANT AND EQUIPMENT,

PROPERTY, PLANT AND EQUIPMENT, NET	9 Months Ended
	Sep. 30, 2017
Property Plant And Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT, NET	4. PROPERTY, PLANT AND EQUIPMENT, NET Details on property, plant and equipment follow. September 30, 2017 December 31, 2016 (In thousands) Gathering and processing systems and related equipment $ 2,075,327 $ 2,026,363 Construction in progress 71,196 39,954 Land and line fill 11,735 11,442 Other 39,675 35,227 Total 2,197,933 2,112,986 Less accumulated depreciation 313,364 259,315 Property, plant and equipment, net $ 1,884,569 $ 1,853,671 Depreciation expense and capitalized interest follow. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Depreciation expense $ 18,837 $ 17,609 $ 55,935 $ 52,574 Capitalized interest 644 1,354 1,562 3,133

AMORTIZING INTANGIBLE ASSETS AN

AMORTIZING INTANGIBLE ASSETS AND UNFAVORABLE GAS GATHERING CONTRACT	9 Months Ended
	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
AMORTIZING INTANGIBLE ASSETS AND UNFAVORABLE GAS GATHERING CONTRACT	5. AMORTIZING INTANGIBLE ASSETS AND UNFAVORABLE GAS GATHERING CONTRACT Details regarding our intangible assets and the unfavorable gas gathering contract (included in other noncurrent liabilities), all of which are subject to amortization, follow. September 30, 2017 Useful lives (In years) Gross carrying amount Accumulated amortization Net (Dollars in thousands) Favorable gas gathering contracts 18.7 $ 24,195 $ (11,962 ) $ 12,233 Contract intangibles 12.5 426,464 (172,120 ) 254,344 Rights-of-way 26.1 155,015 (29,557 ) 125,458 Total intangible assets $ 605,674 $ (213,639 ) $ 392,035 Unfavorable gas gathering contract 10.0 $ 10,962 $ (8,535 ) $ 2,427 December 31, 2016 Useful lives (In years) Gross carrying amount Accumulated amortization Net (Dollars in thousands) Favorable gas gathering contracts 18.7 $ 24,195 $ (10,795 ) $ 13,400 Contract intangibles 12.5 426,464 (146,468 ) 279,996 Rights-of-way 26.1 153,015 (24,959 ) 128,056 Total intangible assets $ 603,674 $ (182,222 ) $ 421,452 Unfavorable gas gathering contract 10.0 $ 10,962 $ (6,916 ) $ 4,046 We recognized amortization expense in other revenues as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Amortization expense – favorable gas gathering contracts $ (390 ) $ (289 ) $ (1,167 ) $ (944 ) Amortization expense – unfavorable gas gathering contract 540 167 1,619 556 We recognized amortization expense in costs and expenses as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Amortization expense – contract intangibles $ 8,550 $ 8,854 $ 25,652 $ 26,562 Amortization expense – rights-of-way 1,540 1,517 4,597 4,534 The estimated aggregate annual amortization expected to be recognized for the remainder of 2017 and each of the four succeeding fiscal years follows. Intangible assets Unfavorable gas gathering contract (In thousands) 2017 $ 10,480 $ 539 2018 41,392 1,888 2019 41,223 — 2020 43,470 — 2021 41,698 —

GOODWILL

GOODWILL	9 Months Ended
	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
GOODWILL	6. GOODWILL We evaluate goodwill for impairment annually on September 30. We also evaluate goodwill whenever events or circumstances indicate that it is more likely than not that the fair value of a reporting unit is less than its carrying value, including goodwill. We test goodwill for impairment using a two-step quantitative test. In the first step, we compare the fair value of the reporting unit to its carrying value, including goodwill. If the reporting unit’s fair value exceeds its carrying value, including goodwill, we conclude that the goodwill of the reporting unit has not been impaired and no further work is performed. If we determine that the reporting unit’s carrying value, including goodwill, exceeds its fair value, we proceed to step two. In step two, we compare the carrying value of the reporting unit, including goodwill, to its implied fair value. If we determine that the carrying value of a reporting unit, including goodwill, exceeds its implied fair value, we recognize the excess of the carrying value over the implied fair value as a goodwill impairment loss. We performed our annual goodwill impairment testing for the Mountaineer Midstream reporting unit as of September 30, 2017, using a combination of the income and market approaches. We determined that the fair value of the Mountaineer Midstream reporting unit substantially exceeded its carrying value, including goodwill; as such, there have been Fair Value Measurement. Our impairment determinations, in the context of (i) our annual impairment evaluations and (ii) our other-than-annual impairment evaluations involved significant assumptions and judgments, as discussed in the 2016 Annual Report. Differing assumptions regarding any of these inputs could have a significant effect on the various valuations. As such, the fair value measurements utilized within these models are classified as non-recurring Level 3 measurements in the fair value hierarchy because they are not observable from objective sources. Due to the volatility of the inputs used, we cannot predict the likelihood of any future impairment.

EQUITY METHOD INVESTMENTS

EQUITY METHOD INVESTMENTS	9 Months Ended
	Sep. 30, 2017
Equity Method Investments And Joint Ventures [Abstract]
EQUITY METHOD INVESTMENTS	7. EQUITY METHOD INVESTMENTS Ohio Gathering owns, operates and is currently developing midstream infrastructure consisting of a liquids-rich natural gas gathering system, a dry natural gas gathering system and a condensate stabilization facility in the Utica Shale in southeastern Ohio. Ohio Gathering provides gathering services pursuant to primarily long-term, fee-based gathering agreements, which include acreage dedications. In June 2017 and June 2016, an impairment loss was recognized by Ohio Gathering. Although we recognize activity for Ohio Gathering on a one-month lag, we recorded the impairment loss in our results of operations for the second quarter of 2017 and 2016 because the information was available to us. We recorded our A reconciliation of our Investment in equity method investees, September 30, 2017 $ 696,590 September cash distribution 4,360 Basis difference (133,522 ) Investment in equity method investees, net of basis difference, August 31, 2017 $ 567,428 Summarized statements of operations information for OGC and OCC follow (amounts represent 100% of investee financial information). Results include asset impairments of Three months ended August 31, 2017 Three months ended August 31, 2016 OGC OCC OGC OCC (In thousands) Total revenues $ 35,144 $ 1,814 $ 34,018 $ 3,478 Total operating expenses 25,720 1,877 24,189 5,092 Net income (loss) 9,424 (204 ) 9,825 (806 ) Nine months ended August 31, 2017 Nine months ended August 31, 2016 OGC OCC OGC OCC (In thousands) Total revenues $ 103,302 $ 5,871 $ 110,261 $ 14,093 Total operating expenses 86,046 6,186 69,294 108,399 Net income (loss) 17,258 (1,396 ) 40,962 (94,051 )

DEFERRED REVENUE

DEFERRED REVENUE	9 Months Ended
	Sep. 30, 2017
Deferred Revenue Disclosure [Abstract]
Deferred Revenue	8. DEFERRED REVENUE A rollforward of current deferred revenue follows. Williston Basin Piceance/DJ Basins Total current (In thousands) Current deferred revenue, January 1, 2017 $ — $ — $ — Additions — 13,584 13,584 Less revenue recognized — 11,211 11,211 Current deferred revenue, September 30, 2017 $ — $ 2,373 $ 2,373 A rollforward of noncurrent deferred revenue follows. Williston Basin Piceance/DJ Basins Total noncurrent (In thousands) Noncurrent deferred revenue, January 1, 2017 $ 37,693 $ 19,772 $ 57,465 Less revenue recognized 37,693 1,978 39,671 Less reclassification to current deferred revenue — 2,373 2,373 Noncurrent deferred revenue, September 30, 2017 $ — $ 15,421 $ 15,421 As of During the first quarter of 2017, we amended an agreement with one of our key customers in the Williston Basin segment. As a result, we recognized previously deferred revenue of

DEBT

DEBT	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
DEBT	9. DEBT Debt consisted of the following: September 30, 2017 December 31, 2016 (In thousands) Summit Holdings variable rate senior secured Revolving Credit Facility (3.74% at September 30, 2017 and 3.27% at December 31, 2016) due May 2022 $ 506,000 $ 648,000 Summit Holdings 5.5% senior unsecured notes due August 2022 300,000 300,000 Less unamortized debt issuance costs (1) (3,049 ) (3,516 ) Summit Holdings 5.75% senior unsecured notes due April 2025 500,000 — Less unamortized debt issuance costs (1) (7,164 ) — Summit Holdings 7.5% senior unsecured notes redeemed March 2017 (2) — 300,000 Less unamortized debt issuance costs (1)(2) — (4,183 ) Total long-term debt $ 1,295,787 $ 1,240,301 (1) Issuance costs are being amortized over the life of the notes. (2) The aggregate amount of debt maturing to be recognized for the remainder of 2017 and each of the four succeeding fiscal years follow (in thousands): 2017 $ — 2018 — 2019 — 2020 — 2021 — Thereafter 1,306,000 Total long-term debt $ 1,306,000 Revolving Credit Facility. Summit Holdings has a senior secured revolving credit facility that allows for revolving loans, letters of credit and swingline loans. On May 26, 2017, Summit Holdings amended and restated its revolving credit facility with a third amended and restated credit agreement which: (i) maintained the revolving credit facility commitments of $1.25 billion, (ii) extended the maturity from November 2018 to May 2022, (iii) includes a $250.0 million accordion feature, (iv) maintained the same leverage-based pricing and commitment fee grid, (v) increased the maximum permitted total leverage ratio, as defined in the credit agreement, from 5.00 to 1.00 to 5.50 to 1.00 and (vi) includes a maximum permitted senior secured leverage ratio, as defined in the credit agreement, of 3.75 to 1.00. Borrowings under the revolving credit facility bear interest, at the election of Summit Holdings, at a rate based on the alternate base rate (as defined in the credit agreement) plus an applicable margin ranging from The revolving credit facility is secured by the membership interests of Summit Holdings and the membership interests of all the subsidiaries of Summit Holdings and by substantially all of the assets of Summit Holdings and its subsidiaries (subject to exclusions set forth in the credit agreement). It is guaranteed by SMLP and all of the subsidiaries of Summit Holdings other than the Specified Subsidiaries (as defined in the credit agreement). The credit agreement contains affirmative and negative covenants customary for credit facilities of its size and nature that, among other things, limit or restrict the ability (i) to incur additional debt; (ii) to make investments; (iii) to engage in certain mergers, consolidations, acquisitions or sales of assets; (iv) to enter into swap agreements and power purchase agreements; (v) to enter into leases that would cumulatively obligate payments in excess of As a result of the amendment, SMLP incurred approximately As of Senior Notes. In June 2013, Summit Holdings and its 100% owned finance subsidiary, Finance Corp. (together with Summit Holdings, the "Co-Issuers") co-issued $300.0 million of 7.5% senior unsecured notes (the "7.5% Senior Notes"). In July 2014, the Co-Issuers co-issued $300.0 million of 5.5% senior unsecured notes maturing August 15, 2022 (the "5.5% Senior Notes" and, together with the 5.75% Senior Notes (defined below, the “Senior Notes”). On February 8, 2017, the Co-Issuers completed a public offering of On June 15, 2017, we executed a supplemental indenture and an amendment to our Revolving Credit Facility to add a newly formed entity, Summit Permian, as a guarantor. As a result, Bison Midstream and its subsidiaries, Grand River and its subsidiary, DFW Midstream, Summit Marketing and Summit Permian (collectively the "Guarantor Subsidiaries") and SMLP fully and unconditionally and jointly and severally guarantee the 5.75% Senior Notes At any time prior to April 15, 2020, the Co-Issuers may redeem up to The The As of and during the nine months ended September 30, 2017, we were in compliance with the covenants governing our Senior Notes. There were no defaults or events of default during the nine months ended September 30, 2017. SMP Holdings Credit Facility. SMP Holdings had a $250.0 million revolving credit facility (the "SMP Revolving Credit Facility") and a $200.0 million term loan (the "Term Loan" and, collectively with the SMP Revolving Credit Facility, the "SMP Holdings Credit Facility"). Because funding from the SMP Holdings Credit Facility was used to support the development of the 2016 Drop Down Assets, Summit Investments allocated the SMP Holdings Credit Facility to the Partnership during the common control period. Borrowings under the SMP Holdings Credit Facility incurred interest at LIBOR or a base rate (as defined in the credit agreement) plus an applicable margin. In March, 2016, the remaining balances on the SMP Revolving Credit Facility and the Incremental Term Loan were repaid in full and the SMP Holdings Credit Facility was terminated concurrent with the closing of the 2016 Drop Down.

FINANCIAL INSTRUMENTS

FINANCIAL INSTRUMENTS	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
FINANCIAL INSTRUMENTS	10. FINANCIAL INSTRUMENTS Concentrations of Credit Risk. Financial instruments that potentially subject us to concentrations of credit risk consist of cash and cash equivalents and accounts receivable. We maintain our cash and cash equivalents in bank deposit accounts that frequently exceed federally insured limits. We have not experienced any losses in such accounts and do not believe we are exposed to any significant risk. Accounts receivable primarily comprise amounts due for the gathering, treating and processing services we provide to our customers and also the sale of natural gas liquids resulting from our processing services. This industry concentration has the potential to impact our overall exposure to credit risk, either positively or negatively, in that our customers may be similarly affected by changes in economic, industry or other conditions. We monitor the creditworthiness of our counterparties and can require letters of credit for receivables from counterparties that are judged to have substandard credit, unless the credit risk can otherwise be mitigated. Our top Fair Value. The carrying amount of cash and cash equivalents, accounts receivable and trade accounts payable reported on the balance sheet approximates fair value due to their short-term maturities. The Deferred Purchase Price Obligation's carrying value is its fair value because carrying value represents the present value of the payment expected to be made in 2020. Our calculation of the Deferred Purchase Price Obligation involves significant assumptions and judgments. Differing assumptions regarding any of these inputs could have a material effect on the ultimate cash payment and the Deferred Purchase Price Obligation. As such, its fair value measurement is classified as a non-recurring Level 3 measurement in the fair value hierarchy because our assumptions and judgments are not observable from objective sources (see Note 16). The Deferred Purchase Price Obligation represents our only Level 3 financial instrument fair value measurement. A rollforward of our Level 3 liability measured at fair value on a recurring basis follows (in thousands). Level 3 liability, January 1, 2017 $ 563,281 Change in fair value (54,674 ) Level 3 liability, September 30, 2017 $ 508,607 A summary of the estimated fair value of our debt financial instruments follows. September 30, 2017 December 31, 2016 Carrying value Estimated fair value (Level 2) Carrying value Estimated fair value (Level 2) (In thousands) Summit Holdings Revolving Credit Facility $ 506,000 $ 506,000 $ 648,000 $ 648,000 Summit Holdings 5.5% Senior Notes ($300.0 million principal) 296,951 301,625 296,484 294,500 Summit Holdings 5.75% Senior Notes ($500.0 million principal) 492,836 506,875 — — Summit Holdings 7.5% Senior Notes ($300.0 million principal) (1) — — 295,817 316,000 (1) Debt was extinguished following the 5.75% Senior Notes offering in February 2017. In conjunction with the early debt extinguishment, the remaining unamortized debt issuance costs were written off. The carrying value on the balance sheet of the Revolving Credit Facility is its fair value due to its floating interest rate. The fair value for the Senior Notes is based on an average of nonbinding broker quotes as of

PARTNERS' CAPITAL

PARTNERS' CAPITAL	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
PARTNERS' CAPITAL	11. PARTNERS' CAPITAL A rollforward of the number of common limited partner and General Partner units follows. Common General Partner Total (In thousands) Units, January 1, 2017 72,111,121 1,471,187 73,582,308 Net units issued under SMLP LTIP 184,277 — 184,277 Units issued under ATM program 763,548 — 763,548 General Partner 2% contribution — 19,812 19,812 Units, September 30, 2017 73,058,946 1,490,999 74,549,945 Unit Offerings. In February 2017, we completed a secondary underwritten public offering of 4,000,000 SMLP common units held by a subsidiary of Summit Investments pursuant to the 2016 SRS. We did not receive any proceeds from this offering. At-the-market Program. In February 2017, we executed a new equity distribution agreement and filed a prospectus and a prospectus supplement with the SEC for the issuance and sale from time to time of SMLP common units having an aggregate offering price of up to $150.0 million (the "ATM Program"). These sales will be made (i) pursuant to the terms of the equity distribution agreement between us and the sales agents named therein and (ii) by means of ordinary brokers' transactions at market prices, in block transactions or as otherwise agreed between us and the sales agents. Sales of our common units may be made in negotiated transactions or transactions that are deemed to be at-the-market offerings as defined by SEC rules. During the three months ended September 30, 2017, there were no Noncontrolling Interest. We have recorded Summit Investments' indirect retained ownership interest in OpCo and its subsidiaries as a noncontrolling interest in the unaudited condensed consolidated financial statements. Summit Investments' Equity in Contributed Subsidiaries. Summit Investments' equity in contributed subsidiaries represents its position in the net assets of the 2016 Drop Down Assets that have been acquired by SMLP. The balance also reflects net income attributable to Summit Investments for the 2016 Drop Down Assets for the periods beginning on their respective acquisition dates by Summit Investments and ending on the date they were acquired by the Partnership. Net income or loss was attributed to Summit Investments for the 2016 Drop Down Assets for the period from January 1, 2016 to March 3, 2016. Although included in partners' capital, any net income or loss attributable to Summit Investments is excluded from the calculation of EPU. Cash Distributions Paid and Declared. We paid the following per-unit distributions during the three and nine months ended September 30: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Per-unit distributions to unitholders $ 0.575 $ 0.575 $ 1.725 $ 1.725 On October 26, 2017, the Board of Directors of our General Partner declared a distribution of $0.575 Incentive Distribution Rights. Our general partner also currently holds IDRs that entitle it to receive increasing percentage allocations, up to a maximum of 50%, of the cash we distribute from operating surplus in excess of $0.46 per unit per quarter. Our payment of IDRs as reported in distributions to unitholders – general partner in the statement of partners' capital during the three and nine months ended September 30 follow. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) IDR payments $ 2,127 $ 1,938 $ 6,333 $ 5,811 For the purposes of calculating net income attributable to General Partner in the statements of operations and partners' capital, the financial impact of IDRs is recognized in respect of the quarter for which the distributions were declared. For the purposes of calculating distributions to unitholders in the statements of partners' capital and cash flows, IDR payments are recognized in the quarter in which they are paid.

EARNINGS PER UNIT

EARNINGS PER UNIT	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
EARNINGS PER UNIT	12. EARNINGS PER UNIT The following table details the components of EPU. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands, except per-unit amounts) Numerator for basic and diluted EPU: Net income (loss) attributable to common units $ 89,547 $ (215 ) $ 95,576 $ (59,702 ) Denominator for basic and diluted EPU: Weighted-average common units outstanding – basic 73,059 67,844 72,583 66,978 Effect of nonvested phantom units 374 — 318 — Weighted-average common units outstanding – diluted 73,433 67,844 72,901 66,978 Earnings (loss) per limited partner unit: Common unit – basic $ 1.23 $ 0.00 $ 1.32 $ (0.89 ) Common unit – diluted $ 1.22 $ 0.00 $ 1.31 $ (0.89 ) Nonvested anti-dilutive phantom units excluded from the calculation of diluted EPU — — 55 167

UNIT-BASED AND NONCASH COMPENSA

UNIT-BASED AND NONCASH COMPENSATION	9 Months Ended
	Sep. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
UNIT-BASED AND NONCASH COMPENSATION	13. UNIT-BASED AND NONCASH COMPENSATION SMLP Long-Term Incentive Plan. The SMLP LTIP provides for equity awards to eligible officers, employees, consultants and directors of our General Partner and its affiliates. Items to note: • In March 2017, we granted • Also in March 2017, • As of

RELATED-PARTY TRANSACTIONS

RELATED-PARTY TRANSACTIONS	9 Months Ended
	Sep. 30, 2017
Related Party Transactions [Abstract]
RELATED-PARTY TRANSACTIONS	14. RELATED-PARTY TRANSACTIONS Acquisitions. For information on the 2016 Drop Down and its funding, see Notes 11 and 16 of the 2016 Annual Report. Reimbursement of Expenses from General Partner. Our General Partner and its affiliates do not receive a management fee or other compensation in connection with the management of our business, but will be reimbursed for expenses incurred on our behalf. Under our Partnership Agreement, we reimburse our General Partner and its affiliates for certain expenses incurred on our behalf, including, without limitation, salary, bonus, incentive compensation and other amounts paid to our General Partner's employees and executive officers who perform services necessary to run our business. Our Partnership Agreement provides that our General Partner will determine in good faith the expenses that are allocable to us. The "Due to affiliate" line item on the consolidated balance sheet represents the payables to our General Partner for expenses incurred by it and paid on our behalf. Expenses incurred by the General Partner and reimbursed by us under our Partnership Agreement were as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Operation and maintenance expense $ 6,792 $ 6,689 $ 20,404 $ 20,061 General and administrative expense 6,840 7,761 23,030 23,218 Expenses Incurred by Summit Investments. Prior to the 2016 Drop Down, Summit Investments incurred: • certain support expenses and capital expenditures on behalf of the contributed subsidiaries. These transactions were settled periodically through membership interests prior to the respective drop down; • interest expense that was related to capital projects for the contributed subsidiaries. As such, the associated interest expense was allocated to the respective contributed subsidiary's capital projects as a noncash contribution and capitalized into the basis of the asset; and • noncash compensation expense for the SMP net profits interests, which were accounted for as compensatory awards. As such, the annual expense associated with the SMP net profits was allocated to the respective contributed subsidiary and is reflected in general and administrative expenses in the statements of operations. Subsequent to any drop down, these expenses are retrospectively included in the reimbursement of General Partner expenses disclosed above due to common control. In February 2017, SMP Holdings sold 4,000,000 common units representing limited partner interests in SMLP at a price to the public of $24.00 per common unit. Consistent with its obligations under our Partnership Agreement, SMLP paid all costs and expenses of the secondary offering (other than underwriting discounts and fees and expenses of counsel and advisors to SMP Holdings in the sale). SMLP did not receive any of the proceeds from the secondary offering.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	15. COMMITMENTS AND CONTINGENCIES Operating Leases. We and Summit Investments lease certain office space and equipment to support our operations. We have determined that our leases are operating leases. We recognize total rent expense incurred or allocated to us in general and administrative expenses. Rent expense related to operating leases, including rent expense incurred on our behalf and allocated to us, was as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Rent expense $ 1,009 $ 754 $ 2,811 $ 2,115 Legal Proceedings. The Partnership is involved in various litigation and administrative proceedings arising in the normal course of business. In the opinion of management, any liabilities that may result from these claims or those arising in the normal course of business would not individually or in the aggregate have a material adverse effect on the Partnership's financial position or results of operations. Environmental Matters. Although we believe that we are in material compliance with applicable environmental regulations, the risk of environmental remediation costs and liabilities are inherent in pipeline ownership and operation. Furthermore, we can provide no assurances that significant environmental remediation costs and liabilities will not be incurred by the Partnership in the future. We are currently not aware of any material contingent liabilities that exist with respect to environmental matters, except as noted below. As described in the 2016 Annual Report, in January 2015, Summit Investments learned of the rupture of a four-inch produced water gathering pipeline on the Meadowlark Midstream system near Williston, North Dakota. The incident, which was covered by Summit Investments' insurance policies, was subject to maximum coverage of A rollforward of the aggregate accrued environmental remediation liabilities follows. Accrued environmental remediation, January 1, 2017 $ 9,453 Payments made (2,935 ) Accrued environmental remediation, September 30, 2017 $ 6,518 As of September 30, 2017, we have recognized (i) a current liability for remediation effort expenditures expected to be incurred within the next 12 months and (ii) a noncurrent liability for estimated remediation expenditures and fines expected to be incurred subsequent to September 30, 2018. Each of these amounts represent our best estimate for costs expected to be incurred. Neither of these amounts has been discounted to its present value. While we cannot predict the ultimate outcome of this matter with certainty for Summit Investments or Meadowlark Midstream, especially as it relates to any material liability as a result of any governmental proceeding related to the incident, we believe at this time that it is unlikely that SMLP or its General Partner will be subject to any material liability as a result of any governmental proceeding related to the rupture.

ACQUISITIONS AND DROP DOWN TRAN

ACQUISITIONS AND DROP DOWN TRANSACTIONS	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
ACQUISITIONS AND DROP DOWN TRANSACTIONS	16. ACQUISITIONS AND DROP DOWN TRANSACTIONS 2016 Drop Down. On March 3, 2016, SMLP acquired a controlling interest in OpCo, the entity which owns the 2016 Drop Down Assets. These assets include certain natural gas, crude oil and produced water gathering systems located in the Utica Shale, the Williston Basin and the DJ Basin as well as ownership interests in a natural gas gathering system and a condensate stabilization facility, both located in the Utica Shale. The net consideration paid and recognized in connection with the 2016 Drop Down (i) consisted of a cash payment to SMP Holdings of The Deferred Purchase Price Obligation will be equal to: • six-and-one-half (6.5) multiplied by the average Business Adjusted EBITDA, as defined below and in the Contribution Agreement, of the 2016 Drop Down Assets for 2018 and 2019, less the G&A Adjuster, as defined in the Contribution Agreement; • less the Initial Payment; • less all capital expenditures incurred for the 2016 Drop Down Assets between the March 3, 2016 and December 31, 2019; • plus all Business Adjusted EBITDA from the 2016 Drop Down Assets between March 3, 2016 and December 31, 2019, less the Cumulative G&A Adjuster, as defined in the Contribution Agreement. Business Adjusted EBITDA is defined as the net income or loss of the 2016 Drop Down Assets for such period: • plus interest expense, income tax expense and depreciation and amortization of the 2016 Drop Down Assets for such period; • plus any adjustments related to MVC shortfall payments, impairments and other noncash expenses or losses with respect to the 2016 Drop Down Assets for such period; • plus any Special Liability Expenses, as defined below and in the Contribution Agreement, for such period; • less interest income and income tax benefit of the 2016 Drop Down Assets for such period; • less adjustments related to any other noncash income or gains with respect to the 2016 Drop Down Assets for such period. Business Adjusted EBITDA shall exclude the effect of any Partnership expenses allocated by or to SMLP or its affiliates in respect of the 2016 Drop Down Assets, such as general and administrative expenses (including compensation-related expenses and professional services fees), transaction costs, allocated interest expense and allocated income tax expense. Special Liability Expenses are defined as any and all expenses incurred by SMLP with respect to the Special Liabilities, as defined in the Contribution Agreement, including fines, legal fees, consulting fees and remediation costs. The present value of the Deferred Purchase Price Obligation will be reflected as a liability on our balance sheet until paid. As of the acquisition date, the estimated future payment obligation (based on management’s estimate of the Partnership’s share of forecasted Business Adjusted EBITDA and capital expenditures for the 2016 Drop Down Assets) was estimated to be At the discretion of the Board of Directors of our General Partner, the Deferred Purchase Price Obligation can be paid in cash, SMLP common units or a combination thereof. We currently expect that the Deferred Purchase Price Obligation will be financed with a combination of (i) net proceeds from the issuance of equity securities by us, (ii) the net proceeds from the issuance of senior unsecured debt by us, (iii) borrowings under our Revolving Credit Facility and/or (iv) other internally generated sources of cash. Because of the common control aspects in a drop down transaction, the 2016 Drop Down was deemed a transaction between entities under common control. As such, the 2016 Drop Down has been accounted for on an “as-if pooled” basis for all periods in which common control existed and the Partnership’s financial results retrospectively include the combined financial results of the 2016 Drop Down Assets for all common-control periods. Supplemental Disclosures – As-If Pooled Basis. As a result of accounting for our drop down transactions similar to a pooling of interests, our historical financial statements and those of the acquired drop down assets have been combined to reflect the historical operations, financial position and cash flows of the acquired drop down assets from the date common control began. Revenues and net income for the previously separate entities and the combined amounts, as presented in these unaudited condensed consolidated financial statements follow. Nine months ended September 30, 2016 (In thousands) SMLP revenues $ 266,412 2016 Drop Down Assets revenues (1) 8,867 Combined revenues $ 275,279 SMLP net loss $ (54,927 ) 2016 Drop Down Assets net income (1) 2,745 Combined net loss $ (52,182 ) (1) Results are fully reflected in SMLP's results of operations subsequent to closing the respective drop down.

CONDENSED CONSOLIDATING FINANCI

CONDENSED CONSOLIDATING FINANCIAL INFORMATION	9 Months Ended
	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
CONDENSED CONSOLIDATING FINANCIAL INFORMATION	17. CONDENSED CONSOLIDATING FINANCIAL INFORMATION The Senior Notes are fully and unconditionally guaranteed, jointly and severally, on a senior unsecured basis by SMLP and the Guarantor Subsidiaries (see Note 9). The following supplemental condensed consolidating financial information reflects SMLP's separate accounts, the combined accounts of the Co-Issuers, the combined accounts of the Guarantor Subsidiaries, the combined accounts of the Non-Guarantor Subsidiaries and the consolidating adjustments for the dates and periods indicated. For purposes of the following consolidating information: • each of SMLP and the Co-Issuers account for their subsidiary investments, if any, under the equity method of accounting; and • the balances and results of operations associated with the assets, liabilities and expenses that were carved out of Summit Investments and allocated to SMLP in connection with the 2016 Drop Down have been attributed to SMLP during the common control period. Condensed Consolidating Balance Sheets. Balance sheets as of September 30, 2017 and December 31, 2016 follow. September 30, 2017 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Assets Cash and cash equivalents $ 492 $ 51 $ 1,528 $ 840 $ — $ 2,911 Accounts receivable 22 — 52,118 9,127 — 61,267 Other current assets 849 — 3,129 807 — 4,785 Due from affiliate — 16,354 488,170 3,392 (507,916 ) — Total current assets 1,363 16,405 544,945 14,166 (507,916 ) 68,963 Property, plant and equipment, net 4,424 — 1,459,053 421,092 — 1,884,569 Intangible assets, net — — 366,967 25,068 — 392,035 Goodwill — — 16,211 — — 16,211 Investment in equity method investees — — — 696,590 — 696,590 Other noncurrent assets 2,588 11,045 120 — — 13,753 Investment in subsidiaries 2,183,363 3,471,883 — — (5,655,246 ) — Total assets $ 2,191,738 $ 3,499,333 $ 2,387,296 $ 1,156,916 $ (6,163,162 ) $ 3,072,121 Liabilities and Partners' Capital Trade accounts payable $ 3,435 $ — $ 12,525 $ 6,716 $ — $ 22,676 Accrued expenses 1,385 — 11,302 1,428 — 14,115 Due to affiliate 508,430 — — — (507,916 ) 514 Deferred revenue — — 2,373 — — 2,373 Ad valorem taxes payable — — 7,687 431 — 8,118 Accrued interest — 20,183 — — — 20,183 Accrued environmental remediation — — — 5,089 — 5,089 Other current liabilities 4,779 — 3,582 602 — 8,963 Total current liabilities 518,029 20,183 37,469 14,266 (507,916 ) 82,031 Long-term debt — 1,295,787 — — — 1,295,787 Deferred Purchase Price Obligation 508,607 — — — — 508,607 Deferred revenue — — 15,421 — — 15,421 Noncurrent accrued environmental remediation — — — 1,429 — 1,429 Other noncurrent liabilities 3,794 — 3,561 183 — 7,538 Total liabilities 1,030,430 1,315,970 56,451 15,878 (507,916 ) 1,910,813 Total partners' capital 1,161,308 2,183,363 2,330,845 1,141,038 (5,655,246 ) 1,161,308 Total liabilities and partners' capital $ 2,191,738 $ 3,499,333 $ 2,387,296 $ 1,156,916 $ (6,163,162 ) $ 3,072,121 December 31, 2016 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Assets Cash and cash equivalents $ 698 $ 51 $ 5,647 $ 1,032 $ — $ 7,428 Accounts receivable 53 — 89,584 7,727 — 97,364 Other current assets 1,526 — 2,328 455 — 4,309 Due from affiliate 14,896 38,013 369,995 — (422,904 ) — Total current assets 17,173 38,064 467,554 9,214 (422,904 ) 109,101 Property, plant and equipment, net 2,266 — 1,440,180 411,225 — 1,853,671 Intangible assets, net — — 396,930 24,522 — 421,452 Goodwill — — 16,211 — — 16,211 Investment in equity method investees — — — 707,415 — 707,415 Other noncurrent assets 1,993 5,198 138 — — 7,329 Investment in subsidiaries 2,132,757 3,347,393 — — (5,480,150 ) — Total assets $ 2,154,189 $ 3,390,655 $ 2,321,013 $ 1,152,376 $ (5,903,054 ) $ 3,115,179 Liabilities and Partners' Capital Trade accounts payable $ 978 $ — $ 9,901 $ 5,372 $ — $ 16,251 Accrued expenses 2,399 114 6,069 2,807 — 11,389 Due to affiliate 408,266 — — 14,896 (422,904 ) 258 Ad valorem taxes payable 16 — 9,717 855 — 10,588 Accrued interest — 17,483 — — — 17,483 Accrued environmental remediation — — — 4,301 — 4,301 Other current liabilities 6,718 — 3,798 955 — 11,471 Total current liabilities 418,377 17,597 29,485 29,186 (422,904 ) 71,741 Long-term debt — 1,240,301 — — — 1,240,301 Deferred Purchase Price Obligation 563,281 — — — — 563,281 Deferred revenue — — 57,465 — — 57,465 Noncurrent accrued environmental remediation — — — 5,152 — 5,152 Other noncurrent liabilities 2,858 — 4,602 106 — 7,566 Total liabilities 984,516 1,257,898 91,552 34,444 (422,904 ) 1,945,506 Total partners' capital 1,169,673 2,132,757 2,229,461 1,117,932 (5,480,150 ) 1,169,673 Total liabilities and partners' capital $ 2,154,189 $ 3,390,655 $ 2,321,013 $ 1,152,376 $ (5,903,054 ) $ 3,115,179 Condensed Consolidating Statements of Operations. For the purposes of the following condensed consolidating statements of operations, we allocate general and administrative expenses recognized at the SMLP parent to the Guarantor Subsidiaries and Non-Guarantor Subsidiaries to reflect what those entities' results would have been had they operated on a stand-alone basis. Statements of operations for the three and nine months ended September 30, 2017 and 2016 follow. Three months ended September 30, 2017 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Revenues: Gathering services and related fees $ — $ — $ 79,546 $ 16,524 $ — $ 96,070 Natural gas, NGLs and condensate sales — — 22,828 112 — 22,940 Other revenues — — 5,202 733 — 5,935 Total revenues — — 107,576 17,369 — 124,945 Costs and expenses: Cost of natural gas and NGLs — — 18,115 62 — 18,177 Operation and maintenance — — 19,044 3,259 — 22,303 General and administrative — — 11,555 1,734 — 13,289 Depreciation and amortization 352 — 24,596 3,979 — 28,927 (Gain) loss on asset sales, net — — (82 ) 542 — 460 Long-lived asset impairment — — 696 594 — 1,290 Total costs and expenses 352 — 73,924 10,170 — 84,446 Other income 79 — — — — 79 Interest expense — (17,614 ) — — — (17,614 ) Deferred Purchase Price Obligation 70,499 — — — — 70,499 Income (loss) before income taxes and income from equity method investees 70,226 (17,614 ) 33,652 7,199 — 93,463 Income tax expense (176 ) — — — — (176 ) Income from equity method investees — — — 350 — 350 Equity in earnings of consolidated subsidiaries 23,587 41,201 — — (64,788 ) — Net income $ 93,637 $ 23,587 $ 33,652 $ 7,549 $ (64,788 ) $ 93,637 Three months ended September 30, 2016 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Revenues: Gathering services and related fees $ — $ — $ 64,065 $ 16,231 $ — $ 80,296 Natural gas, NGLs and condensate sales — — 9,578 — — 9,578 Other revenues — — 4,612 587 — 5,199 Total revenues — — 78,255 16,818 — 95,073 Costs and expenses: Cost of natural gas and NGLs — — 6,986 — — 6,986 Operation and maintenance — — 20,800 2,259 — 23,059 General and administrative — — 10,183 2,185 — 12,368 Depreciation and amortization 154 — 24,765 3,060 — 27,979 Loss on asset sales, net — — 13 — — 13 Long-lived asset impairment — — 1,172 — — 1,172 Total costs and expenses 154 — 63,919 7,504 — 71,577 Other income 51 — — — — 51 Interest expense — (15,733 ) — — — (15,733 ) Deferred Purchase Price Obligation (6,188 ) — — — — (6,188 ) (Loss) income before income taxes and income from equity method investees (6,291 ) (15,733 ) 14,336 9,314 — 1,626 Income tax benefit 142 — — — — 142 Income from equity method investees — — — 270 — 270 Equity in earnings of consolidated subsidiaries 8,187 23,920 — — (32,107 ) — Net income $ 2,038 $ 8,187 $ 14,336 $ 9,584 $ (32,107 ) $ 2,038 Nine months ended September 30, 2017 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Revenues: Gathering services and related fees $ — $ — $ 245,882 $ 53,002 $ — $ 298,884 Natural gas, NGLs and condensate sales — — 44,355 300 — 44,655 Other revenues — — 17,043 1,960 — 19,003 Total revenues — — 307,280 55,262 — 362,542 Costs and expenses: Cost of natural gas and NGLs — — 36,243 85 — 36,328 Operation and maintenance — — 60,812 9,199 — 70,011 General and administrative — — 34,317 6,053 — 40,370 Depreciation and amortization 660 — 73,817 11,707 — 86,184 Transaction costs 119 — — — — 119 Gain (loss) on asset sales, net — — (14 ) 544 — 530 Long-lived asset impairment — — 698 879 — 1,577 Total costs and expenses 779 — 205,873 28,467 — 235,119 Other income 214 — — — — 214 Interest expense — (51,883 ) — — — (51,883 ) Early extinguishment of debt — (22,020 ) — — — (22,020 ) Deferred Purchase Price Obligation 54,674 — — — — 54,674 Income (loss) before income taxes and loss from equity method investees 54,109 (73,903 ) 101,407 26,795 — 108,408 Income tax expense (417 ) — — — — (417 ) Loss from equity method investees — — — (3,691 ) — (3,691 ) Equity in earnings of consolidated subsidiaries 50,608 124,511 — — (175,119 ) — Net income $ 104,300 $ 50,608 $ 101,407 $ 23,104 $ (175,119 ) $ 104,300 Nine months ended September 30, 2016 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Revenues: Gathering services and related fees $ — $ — $ 191,510 $ 43,073 $ — $ 234,583 Natural gas, NGLs and condensate sales — — 25,747 — — 25,747 Other revenues — — 13,286 1,663 — 14,949 Total revenues — — 230,543 44,736 — 275,279 Costs and expenses: Cost of natural gas and NGLs — — 20,140 — — 20,140 Operation and maintenance — — 64,413 7,898 — 72,311 General and administrative — — 31,072 7,051 — 38,123 Depreciation and amortization 424 — 74,194 9,052 — 83,670 Transaction costs 1,296 — — — — 1,296 Loss on asset sales, net — — 24 — — 24 Long-lived asset impairment — — 1,212 529 — 1,741 Total costs and expenses 1,720 — 191,055 24,530 — 217,305 Other income 92 — — — — 92 Interest expense (1,441 ) (46,209 ) — — — (47,650 ) Deferred Purchase Price Obligation (31,116 ) — — — — (31,116 ) (Loss) income before income taxes and loss from equity method investees (34,185 ) (46,209 ) 39,488 20,206 — (20,700 ) Income tax expense (141 ) — — — — (141 ) Loss from equity method investees — — — (31,341 ) — (31,341 ) Equity in (loss) earnings of consolidated subsidiaries (17,856 ) 28,353 — — (10,497 ) — Net (loss) income $ (52,182 ) $ (17,856 ) $ 39,488 $ (11,135 ) $ (10,497 ) $ (52,182 ) Condensed Consolidating Statements of Cash Flows. Statements of cash flows for the nine months ended September 30, 2017 and 2016 follow. Nine months ended September 30, 2017 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Cash flows from operating activities: Net cash provided by (used in) operating activities $ 5,707 $ (45,854 ) $ 174,335 $ 62,309 $ — $ 196,497 Cash flows from investing activities: Capital expenditures (995 ) — (60,279 ) (24,932 ) — (86,206 ) Proceeds from asset sales — — — 2,300 — 2,300 Contributions to equity method investees — — — (21,581 ) — (21,581 ) Other, net (579 ) — — — — (579 ) Advances to affiliates 14,896 21,658 (118,175 ) (3,392 ) 85,013 — Net cash provided by (used in) investing activities 13,322 21,658 (178,454 ) (47,605 ) 85,013 (106,066 ) Cash flows from financing activities: Distributions to unitholders (134,066 ) — — — — (134,066 ) Borrowings under Revolving Credit Facility — 177,500 — — — 177,500 Repayments under Revolving Credit Facility — (319,500 ) — — — (319,500 ) Debt issuance costs — (15,891 ) — — — (15,891 ) Payment of redemption and call premiums on senior notes — (17,913 ) — — — (17,913 ) Proceeds from ATM Program issuances, net of costs 17,251 — — — — 17,251 Contribution from General Partner 465 — — — — 465 Issuance of senior notes — 500,000 — — — 500,000 Tender and redemption of senior notes — (300,000 ) — — — (300,000 ) Other, net (2,794 ) — — — — (2,794 ) Advances from affiliates 99,909 — — (14,896 ) (85,013 ) — Net cash (used in) provided by financing activities (19,235 ) 24,196 — (14,896 ) (85,013 ) (94,948 ) Net change in cash and cash equivalents (206 ) — (4,119 ) (192 ) — (4,517 ) Cash and cash equivalents, beginning of period 698 51 5,647 1,032 — 7,428 Cash and cash equivalents, end of period $ 492 $ 51 $ 1,528 $ 840 $ — $ 2,911 Nine months ended September 30, 2016 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Cash flows from operating activities: Net cash provided by (used in) operating activities $ 3,740 $ (52,916 ) $ 159,650 $ 58,231 $ — $ 168,705 Cash flows from investing activities: Capital expenditures (904 ) — (39,630 ) (82,201 ) — (122,735 ) Contributions to equity method investees — — — (20,157 ) — (20,157 ) Acquisitions of gathering systems from affiliate (359,431 ) — — — — (359,431 ) Other, net (373 ) — — — — (373 ) Advances to affiliates (16,822 ) (245,093 ) (124,843 ) — 386,758 — Net cash used in investing activities (377,530 ) (245,093 ) (164,473 ) (102,358 ) 386,758 (502,696 ) Cash flows from financing activities: Distributions to unitholders (123,064 ) — — — — (123,064 ) Borrowings under Revolving Credit Facility 12,000 478,300 — — — 490,300 Repayments under Revolving Credit Facility — (189,300 ) — — — (189,300 ) Debt issuance costs — (3,013 ) — — — (3,013 ) Proceeds from issuance of common units, net 126,115 — — — — 126,115 Contribution from General Partner 2,702 — — — — 2,702 Cash advance from Summit Investments to contributed subsidiaries, net (12,000 ) — — 24,214 — 12,214 Expenses paid by Summit Investments on behalf of contributed subsidiaries 3,030 — — 1,791 — 4,821 Other, net (980 ) — — — — (980 ) Advances from affiliates 369,936 — — 16,822 (386,758 ) — Net cash provided by financing activities 377,739 285,987 — 42,827 (386,758 ) 319,795 Net change in cash and cash equivalents 3,949 (12,022 ) (4,823 ) (1,300 ) — (14,196 ) Cash and cash equivalents, beginning of period 73 12,407 6,930 2,383 — 21,793 Cash and cash equivalents, end of period $ 4,022 $ 385 $ 2,107 $ 1,083 $ — $ 7,597

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	9 Months Ended
	Sep. 30, 2017
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	18. SUBSEQUENT EVENTS We have evaluated subsequent events for recognition or disclosure in the unaudited condensed consolidated financial statements filed on Form 10-Q with the SEC and no events have occurred that require disclosure.

SUMMARY OF SIGNIFICANT ACCOUN25

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Accounting Pronouncements	There have been no changes to our significant accounting policies since December 31, 2016. Recent Accounting Pronouncements. Accounting standard setters frequently issue new or revised accounting rules. We review new pronouncements to determine the impact, if any, on our financial statements. Accounting standards that have or could possibly have a material effect on our financial statements are discussed below. Recently Adopted Accounting Pronouncements • ASU No. 2016-09 Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting ("ASU 2016-09"). ASU 2016-09 simplifies several aspects for share-based payment award transactions, including income tax consequences, the liability or equity classification of awards and classification on the statements of cash flows. ASU 2016-09 is effective for public companies for fiscal years beginning after December 15, 2016. It does not specify a single transition approach, rather it specifies retrospective, modified retrospective and/or prospective transition approaches based on the aspect being applied. We adopted the provisions of ASU 2016-09 effective January 1, 2017. The adoption of this standard had no impact on our consolidated financial statements. Accounting Pronouncements Pending Adoption • ASU No. 2014-09 Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09"). Under ASU 2014-09, revenue will be recognized under a five-step model: (i) identify the contract with the customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to performance obligations; and (v) recognize revenue when (or as) the performance obligation is satisfied. ASU 2014-09 is effective for fiscal years and interim periods within those years, beginning after December 15, 2017 and allows for early adoption. We expect to adopt the provisions of ASU 2014-09 effective January 1, 2018 using the modified retrospective method. We have completed reviewing our existing contract portfolio in place as of September 30, 2017 under ASU 2014-09 and have quantified the expected impact of adoption. For contracts where we perform gathering services and earn a per-unit fee which is recognized at a point in time, revenue will be recognized over time as the service is performed and will result in revenue recognition materially consistent with current GAAP. In addition, our contracts generally contain forms of what will be considered variable consideration, which will likely be constrained as the volumes are susceptible to factors outside of our control and influence. As a result of applying the constraint guidance, timing of revenue recognition will be materially consistent with current GAAP. However, we will be billing amounts that correspond directly to the value transferred such that the resulting revenue recognized will be consistent with current GAAP. Contributions in aid of construction received prior to adoption were recognized as a reduction to property, plant and equipment. Upon adoption of the new guidance, those amounts will be capitalized to property, plant and equipment, net of any accumulated depreciation, and depreciated over the remaining useful lives. Going forward, any contributions in aid of construction will be recognized as revenue over the remaining term of the respective contract in accordance with ASU 2014-09. The cumulative expected impact upon adoption for contributions in aid of construction is anticipated to be a net increase in property, plant and equipment of between $30.0 and $33.0 million, a net increase in partners’ capital of between $8.0 and $10.0 million and an increase in deferred revenue of between $22.0 and $25.0 million. The cumulative expected impact upon adoption for facility fees will be a decrease in partners’ capital of between $11.0 and $13.0 million and an increase in deferred revenue of between $11.0 and $13.0 million. We are continuing to work with our midstream industry peers to develop our position on certain implementation matters including the presentation and disclosure of percent-of-proceeds contracts. We will finalize our assessment of the adoption of ASU 2014-09 and will disclose any further updates along with the practical expedients we expect to utilize in our Form 10-K for the year ended December 31, 2017. • ASU No. 2016-02 Leases (Topic 842) ("ASU 2016-02"). ASU 2016-02 requires that lessees recognize all leases on the balance sheet, with the exception of short-term leases. A lease liability will be recorded for the obligation of a lessee to make lease payments arising from a lease. A right-of-use asset will be recorded which represents the lessee’s right to use, or to control the use of, a specified asset for a lease term. We are currently evaluating the impact of this guidance on lessor accounting but have made no determinations at this time. ASU 2016-02 is effective for public companies for fiscal years beginning after December 15, 2018, and requires the modified retrospective approach for transition. We are currently evaluating the provisions of ASU 2016-02 to determine its impact on our financial statements and related disclosures and expect to adopt its provisions effective January 1, 2019. • ASU No. 2016-08 Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net) ("ASU 2016-08"). ASU 2016-08 does not change the core principle of Topic 606, rather it clarifies the implementation guidance on principal versus agent considerations. We expect to adopt the provisions of ASU 2016-08 effective January 1, 2018. Our position regarding the impact of and transition method for this update is the same as for ASU 2014-09. • ASU No. 2016-10 Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing ("ASU 2016-10"). ASU 2016-10 clarifies the following two aspects of Topic 606: (i) identifying performance obligations; and (ii) the licensing implementation guidance, while retaining the related principles for those areas. We expect to adopt the provisions of ASU 2016-10 effective January 1, 2018. Our position regarding the impact of and transition method for this update is the same as for ASU 2014-09. • ASU No. 2016-12 Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients ("ASU 2016-12"). ASU 2016-12 does not change the core principle of the guidance in Topic 606. Rather, the amendments therein affect only the narrow aspects of Topic 606 including assessing the collectability criterion and issues related to contract modification at transition and completed contracts at transition. We expect to adopt the provisions of ASU 2016-12 effective January 1, 2018. Our position regarding the impact of and transition method for this update is the same as for ASU 2014-09.
Basis of Presentation	Presentation and Consolidation. We prepare our unaudited condensed consolidated financial statements in accordance with GAAP as established by the FASB. We make estimates and assumptions that affect the reported amounts of assets and liabilities at the balance sheet dates, including fair value measurements, the reported amounts of revenue and expense and the disclosure of contingencies. Although management believes these estimates are reasonable, actual results could differ from its estimates. The unaudited condensed consolidated financial statements include the assets, liabilities and results of operations of SMLP and its subsidiaries. All intercompany transactions among the consolidated entities have been eliminated in consolidation. Comprehensive income or loss is the same as net income or loss for all periods presented. The financial position, results of operations and cash flows of acquired drop down assets, liabilities, expenses or entities that were carved out of entities held by Summit Investments and included herein have been derived from the accounting records of the respective Summit Investments' subsidiary on a carve-out basis. SMLP recognized its drop down acquisitions at Summit Investments' historical cost because the acquisitions were executed by entities under common control. The excess of Summit Investments' net investment over the consideration paid and recognized for a contributed subsidiary is recognized as an addition to partners' capital, while the excess of purchase price paid and recognized over net investment is recognized as a reduction to partners' capital. Due to the common control aspect, we account for drop down transactions on an “as-if pooled” basis for the periods during which common control existed. These unaudited condensed consolidated financial statements have been prepared pursuant to the rules and the regulations of the SEC. Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations. We believe that the disclosures made are adequate to make the information not misleading. In the opinion of management, the unaudited condensed consolidated financial statements contain all adjustments, including normal recurring adjustments, which are necessary to fairly present the unaudited condensed consolidated balance sheet as of September 30, 2017, the unaudited condensed consolidated statements of operations for the three and nine month periods ended September 30, 2017 and 2016 and the unaudited condensed consolidated statements of partners' capital and cash flows for the nine month periods ended September 30, 2017 and 2016. The balance sheet at December 31, 2016 included herein was derived from our audited financial statements, but does not include all disclosures required by GAAP. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto that are included in our annual report on Form 10-K for the year ended December 31, 2016, as filed with the SEC on February 27, 2017 (the "2016 Annual Report"). The results of operations for an interim period are not necessarily indicative of results expected for a full year.

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Schedule of assets by reportable segment	Assets by reportable segment follow. September 30, 2017 December 31, 2016 (In thousands) Assets: Utica Shale $ 212,339 $ 199,392 Ohio Gathering 696,590 707,415 Williston Basin 695,120 724,084 Piceance/DJ Basins 799,410 843,440 Barnett Shale 389,026 404,314 Marcellus Shale 219,909 224,709 Total reportable segment assets 3,012,394 3,103,354 Corporate and other 60,699 12,294 Eliminations (972 ) (469 ) Total assets $ 3,072,121 $ 3,115,179
Schedule of segment reporting information	Revenues by reportable segment follow. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Revenues (1): Utica Shale $ 9,727 $ 7,665 $ 28,979 $ 17,351 Williston Basin 27,821 30,194 123,820 87,710 Piceance/DJ Basins 53,875 31,076 122,446 89,479 Barnett Shale 16,694 19,490 55,340 60,747 Marcellus Shale 8,160 6,648 22,429 19,992 Total reportable segments revenue 116,277 95,073 353,014 275,279 Corporate and other 11,816 — 14,964 — Eliminations (3,148 ) — (5,436 ) — Total revenues $ 124,945 $ 95,073 $ 362,542 $ 275,279 (1) Excludes revenues earned by Ohio Gathering due to equity method accounting. Depreciation and amortization, including the amortization expense associated with our favorable and unfavorable gas gathering contracts as reported in other revenues, by reportable segment follows. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Depreciation and amortization (1): Utica Shale $ 1,818 $ 961 $ 5,213 $ 2,756 Williston Basin 8,405 8,446 25,171 25,214 Piceance/DJ Basins 12,199 12,273 36,635 36,843 Barnett Shale (2) 3,735 4,043 11,259 12,155 Marcellus Shale 2,268 2,224 6,794 6,665 Total reportable segment depreciation and amortization 28,425 27,947 85,072 83,633 Corporate and other 352 154 660 425 Total depreciation and amortization $ 28,777 $ 28,101 $ 85,732 $ 84,058 (1) Excludes depreciation and amortization recognized by Ohio Gathering due to equity method accounting. (2) Includes the amortization expense associated with our favorable and unfavorable gas gathering contracts as reported in other revenues. Cash paid for capital expenditures by reportable segment follow. Nine months ended September 30, 2017 2016 (In thousands) Cash paid for capital expenditures (1): Utica Shale $ 21,425 $ 72,036 Williston Basin 13,735 30,687 Piceance/DJ Basins 17,902 15,421 Barnett Shale 119 2,716 Marcellus Shale 628 971 Total reportable segment capital expenditures 53,809 121,831 Corporate and other 32,397 904 Total cash paid for capital expenditures $ 86,206 $ 122,735 (1) Excludes cash paid for capital expenditures by Ohio Gathering due to equity method accounting.
Schedule of counterparties accounting for more than 10% of total revenues	Counterparties accounting for more than 10% of total revenues were as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Percentage of total revenues (1)(2): Counterparty A - Piceance/DJ Basins 17 % * * * Counterparty B - Williston Basin * * 16 % * Counterparty C - Piceance/DJ Basins * 10 % * * (1) Includes recognition of revenue that was previously deferred in connection with minimum volume commitments (see Note 8). (2) Excludes revenues earned by Ohio Gathering due to equity method accounting. * Less than 10%
Reconciliation of net income to adjusted EBITDA	Segment adjusted EBITDA by reportable segment follows. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Reportable segment adjusted EBITDA Utica Shale $ 8,412 $ 6,983 $ 25,857 $ 14,898 Ohio Gathering 10,522 10,059 29,201 35,173 Williston Basin 16,212 21,815 51,176 60,745 Piceance/DJ Basins 30,008 28,074 86,256 79,120 Barnett Shale 10,838 13,128 35,924 41,118 Marcellus Shale 6,682 5,146 17,775 14,554 Total of reportable segments' measures of profit or loss $ 82,674 $ 85,205 $ 246,189 $ 245,608 A reconciliation of income or loss before income taxes and loss from equity method investees to total of reportable segments' measures of profit or loss follows. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Reconciliation of income or loss before income taxes and income or loss from equity method investees to total of reportable segments' measures of profit or loss: Income (loss) before income taxes and income (loss) from equity method investees $ 93,463 $ 1,626 $ 108,408 $ (20,700 ) Add: Corporate and other 9,197 8,722 28,725 26,728 Interest expense 17,614 15,733 51,883 47,650 Early extinguishment of debt — — 22,020 — Deferred Purchase Price Obligation (70,499 ) 6,188 (54,674 ) 31,116 Depreciation and amortization 28,777 28,101 85,732 84,058 Proportional adjusted EBITDA for equity method investees 10,522 10,059 29,201 35,173 Adjustments related to MVC shortfall payments (10,124 ) 11,541 (33,186 ) 33,818 Unit-based and noncash compensation 1,974 2,050 5,973 6,000 Loss on asset sales, net 460 13 530 24 Long-lived asset impairment 1,290 1,172 1,577 1,741 Total of reportable segments' measures of profit or loss $ 82,674 $ 85,205 $ 246,189 $ 245,608
Schedule of Adjustments Related to Minimum Volume Commitments Shortfall Payments	Adjustments related to MVC shortfall payments by reportable segment follow. Three months ended September 30, 2017 Williston Basin Piceance/DJ Basins Barnett Shale Total (In thousands) Adjustments related to MVC shortfall payments: Net change in deferred revenue for MVC shortfall payments $ — $ — $ — $ — Expected MVC shortfall adjustments 1,982 (12,200 ) 94 (10,124 ) Total adjustments related to MVC shortfall payments $ 1,982 $ (12,200 ) $ 94 $ (10,124 ) Three months ended September 30, 2016 Williston Basin Piceance/DJ Basins Barnett Shale Total (In thousands) Adjustments related to MVC shortfall payments: Net change in deferred revenue for MVC shortfall payments $ — $ 847 $ — $ 847 Expected MVC shortfall adjustments 4,195 6,412 87 10,694 Total adjustments related to MVC shortfall payments $ 4,195 $ 7,259 $ 87 $ 11,541 Nine months ended September 30, 2017 Williston Basin Piceance/DJ Basins Barnett Shale Total (In thousands) Adjustments related to MVC shortfall payments: Net change in deferred revenue for MVC shortfall payments $ (37,693 ) $ (1,978 ) $ — $ (39,671 ) Expected MVC shortfall adjustments 5,946 867 (328 ) 6,485 Total adjustments related to MVC shortfall payments $ (31,747 ) $ (1,111 ) $ (328 ) $ (33,186 ) Nine months ended September 30, 2016 Williston Basin Piceance/DJ Basins Barnett Shale Total (In thousands) Adjustments related to MVC shortfall payments: Net change in deferred revenue for MVC shortfall payments $ 235 $ 3,321 $ (677 ) $ 2,879 Expected MVC shortfall adjustments 11,757 18,911 271 30,939 Total adjustments related to MVC shortfall payments $ 11,992 $ 22,232 $ (406 ) $ 33,818

PROPERTY, PLANT AND EQUIPMENT27

PROPERTY, PLANT AND EQUIPMENT, NET (Tables)	9 Months Ended
	Sep. 30, 2017
Property Plant And Equipment [Abstract]
Schedule of property, plant, and equipment, net	Details on property, plant and equipment follow. September 30, 2017 December 31, 2016 (In thousands) Gathering and processing systems and related equipment $ 2,075,327 $ 2,026,363 Construction in progress 71,196 39,954 Land and line fill 11,735 11,442 Other 39,675 35,227 Total 2,197,933 2,112,986 Less accumulated depreciation 313,364 259,315 Property, plant and equipment, net $ 1,884,569 $ 1,853,671
Schedule of depreciation expense and capitalized interest	Depreciation expense and capitalized interest follow. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Depreciation expense $ 18,837 $ 17,609 $ 55,935 $ 52,574 Capitalized interest 644 1,354 1,562 3,133

AMORTIZING INTANGIBLE ASSETS 28

AMORTIZING INTANGIBLE ASSETS AND UNFAVORABLE GAS GATHERING CONTRACT (Tables)	9 Months Ended
	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible assets and liabilities subject to amortization	Details regarding our intangible assets and the unfavorable gas gathering contract (included in other noncurrent liabilities), all of which are subject to amortization, follow. September 30, 2017 Useful lives (In years) Gross carrying amount Accumulated amortization Net (Dollars in thousands) Favorable gas gathering contracts 18.7 $ 24,195 $ (11,962 ) $ 12,233 Contract intangibles 12.5 426,464 (172,120 ) 254,344 Rights-of-way 26.1 155,015 (29,557 ) 125,458 Total intangible assets $ 605,674 $ (213,639 ) $ 392,035 Unfavorable gas gathering contract 10.0 $ 10,962 $ (8,535 ) $ 2,427 December 31, 2016 Useful lives (In years) Gross carrying amount Accumulated amortization Net (Dollars in thousands) Favorable gas gathering contracts 18.7 $ 24,195 $ (10,795 ) $ 13,400 Contract intangibles 12.5 426,464 (146,468 ) 279,996 Rights-of-way 26.1 153,015 (24,959 ) 128,056 Total intangible assets $ 603,674 $ (182,222 ) $ 421,452 Unfavorable gas gathering contract 10.0 $ 10,962 $ (6,916 ) $ 4,046
Recognized amortization expense in other revenues and cost and expenses	We recognized amortization expense in other revenues as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Amortization expense – favorable gas gathering contracts $ (390 ) $ (289 ) $ (1,167 ) $ (944 ) Amortization expense – unfavorable gas gathering contract 540 167 1,619 556 We recognized amortization expense in costs and expenses as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Amortization expense – contract intangibles $ 8,550 $ 8,854 $ 25,652 $ 26,562 Amortization expense – rights-of-way 1,540 1,517 4,597 4,534
Estimated aggregate annual amortization expected to be recognized	The estimated aggregate annual amortization expected to be recognized for the remainder of 2017 and each of the four succeeding fiscal years follows. Intangible assets Unfavorable gas gathering contract (In thousands) 2017 $ 10,480 $ 539 2018 41,392 1,888 2019 41,223 — 2020 43,470 — 2021 41,698 —

EQUITY METHOD INVESTMENTS (Tabl

EQUITY METHOD INVESTMENTS (Tables)	9 Months Ended
	Sep. 30, 2017
Equity Method Investments And Joint Ventures [Abstract]
Equity Method Investments	A reconciliation of our Investment in equity method investees, September 30, 2017 $ 696,590 September cash distribution 4,360 Basis difference (133,522 ) Investment in equity method investees, net of basis difference, August 31, 2017 $ 567,428 Summarized statements of operations information for OGC and OCC follow (amounts represent 100% of investee financial information). Results include asset impairments of Three months ended August 31, 2017 Three months ended August 31, 2016 OGC OCC OGC OCC (In thousands) Total revenues $ 35,144 $ 1,814 $ 34,018 $ 3,478 Total operating expenses 25,720 1,877 24,189 5,092 Net income (loss) 9,424 (204 ) 9,825 (806 ) Nine months ended August 31, 2017 Nine months ended August 31, 2016 OGC OCC OGC OCC (In thousands) Total revenues $ 103,302 $ 5,871 $ 110,261 $ 14,093 Total operating expenses 86,046 6,186 69,294 108,399 Net income (loss) 17,258 (1,396 ) 40,962 (94,051 )

DEFERRED REVENUE (Tables)

DEFERRED REVENUE (Tables)	9 Months Ended
	Sep. 30, 2017
Deferred Revenue Disclosure [Abstract]
Rollforward of deferred revenue	A rollforward of current deferred revenue follows. Williston Basin Piceance/DJ Basins Total current (In thousands) Current deferred revenue, January 1, 2017 $ — $ — $ — Additions — 13,584 13,584 Less revenue recognized — 11,211 11,211 Current deferred revenue, September 30, 2017 $ — $ 2,373 $ 2,373 A rollforward of noncurrent deferred revenue follows. Williston Basin Piceance/DJ Basins Total noncurrent (In thousands) Noncurrent deferred revenue, January 1, 2017 $ 37,693 $ 19,772 $ 57,465 Less revenue recognized 37,693 1,978 39,671 Less reclassification to current deferred revenue — 2,373 2,373 Noncurrent deferred revenue, September 30, 2017 $ — $ 15,421 $ 15,421

DEBT (Tables)

DEBT (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Schedule of debt and capital leases	Debt consisted of the following: September 30, 2017 December 31, 2016 (In thousands) Summit Holdings variable rate senior secured Revolving Credit Facility (3.74% at September 30, 2017 and 3.27% at December 31, 2016) due May 2022 $ 506,000 $ 648,000 Summit Holdings 5.5% senior unsecured notes due August 2022 300,000 300,000 Less unamortized debt issuance costs (1) (3,049 ) (3,516 ) Summit Holdings 5.75% senior unsecured notes due April 2025 500,000 — Less unamortized debt issuance costs (1) (7,164 ) — Summit Holdings 7.5% senior unsecured notes redeemed March 2017 (2) — 300,000 Less unamortized debt issuance costs (1)(2) — (4,183 ) Total long-term debt $ 1,295,787 $ 1,240,301 (1) Issuance costs are being amortized over the life of the notes. (2)
Schedule of maturities of long-term debt	The aggregate amount of debt maturing to be recognized for the remainder of 2017 and each of the four succeeding fiscal years follow (in thousands): 2017 $ — 2018 — 2019 — 2020 — 2021 — Thereafter 1,306,000 Total long-term debt $ 1,306,000

FINANCIAL INSTRUMENTS (Tables)

FINANCIAL INSTRUMENTS (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair value of liabilities measured on recurring basis, unobservable input reconciliation	A rollforward of our Level 3 liability measured at fair value on a recurring basis follows (in thousands). Level 3 liability, January 1, 2017 $ 563,281 Change in fair value (54,674 ) Level 3 liability, September 30, 2017 $ 508,607
Summary of the estimated fair value of debt instruments	A summary of the estimated fair value of our debt financial instruments follows. September 30, 2017 December 31, 2016 Carrying value Estimated fair value (Level 2) Carrying value Estimated fair value (Level 2) (In thousands) Summit Holdings Revolving Credit Facility $ 506,000 $ 506,000 $ 648,000 $ 648,000 Summit Holdings 5.5% Senior Notes ($300.0 million principal) 296,951 301,625 296,484 294,500 Summit Holdings 5.75% Senior Notes ($500.0 million principal) 492,836 506,875 — — Summit Holdings 7.5% Senior Notes ($300.0 million principal) (1) — — 295,817 316,000 (1) Debt was extinguished following the 5.75% Senior Notes offering in February 2017. In conjunction with the early debt extinguishment, the remaining unamortized debt issuance costs were written off.

PARTNERS' CAPITAL (Tables)

PARTNERS' CAPITAL (Tables)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Schedule of partner units activity	A rollforward of the number of common limited partner and General Partner units follows. Common General Partner Total (In thousands) Units, January 1, 2017 72,111,121 1,471,187 73,582,308 Net units issued under SMLP LTIP 184,277 — 184,277 Units issued under ATM program 763,548 — 763,548 General Partner 2% contribution — 19,812 19,812 Units, September 30, 2017 73,058,946 1,490,999 74,549,945
Details of cash distributions	We paid the following per-unit distributions during the three and nine months ended September 30: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Per-unit distributions to unitholders $ 0.575 $ 0.575 $ 1.725 $ 1.725 Our payment of IDRs as reported in distributions to unitholders – general partner in the statement of partners' capital during the three and nine months ended September 30 follow. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) IDR payments $ 2,127 $ 1,938 $ 6,333 $ 5,811

EARNINGS PER UNIT (Tables)

EARNINGS PER UNIT (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Schedule of earnings per limited partner unit	The following table details the components of EPU. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands, except per-unit amounts) Numerator for basic and diluted EPU: Net income (loss) attributable to common units $ 89,547 $ (215 ) $ 95,576 $ (59,702 ) Denominator for basic and diluted EPU: Weighted-average common units outstanding – basic 73,059 67,844 72,583 66,978 Effect of nonvested phantom units 374 — 318 — Weighted-average common units outstanding – diluted 73,433 67,844 72,901 66,978 Earnings (loss) per limited partner unit: Common unit – basic $ 1.23 $ 0.00 $ 1.32 $ (0.89 ) Common unit – diluted $ 1.22 $ 0.00 $ 1.31 $ (0.89 ) Nonvested anti-dilutive phantom units excluded from the calculation of diluted EPU — — 55 167

RELATED-PARTY TRANSACTIONS (Tab

RELATED-PARTY TRANSACTIONS (Tables)	9 Months Ended
	Sep. 30, 2017
Related Party Transactions [Abstract]
Schedule of related party transactions	Expenses incurred by the General Partner and reimbursed by us under our Partnership Agreement were as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Operation and maintenance expense $ 6,792 $ 6,689 $ 20,404 $ 20,061 General and administrative expense 6,840 7,761 23,030 23,218

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Schedule of total rent expense related to operating leases	Rent expense related to operating leases, including rent expense incurred on our behalf and allocated to us, was as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 (In thousands) Rent expense $ 1,009 $ 754 $ 2,811 $ 2,115
Schedule of accrued environmental remediation	A rollforward of the aggregate accrued environmental remediation liabilities follows. Accrued environmental remediation, January 1, 2017 $ 9,453 Payments made (2,935 ) Accrued environmental remediation, September 30, 2017 $ 6,518

ACQUISITIONS AND DROP DOWN TR37

ACQUISITIONS AND DROP DOWN TRANSACTIONS (Tables)	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Business Combination, Revenue and Net Income Disclosures	Revenues and net income for the previously separate entities and the combined amounts, as presented in these unaudited condensed consolidated financial statements follow. Nine months ended September 30, 2016 (In thousands) SMLP revenues $ 266,412 2016 Drop Down Assets revenues (1) 8,867 Combined revenues $ 275,279 SMLP net loss $ (54,927 ) 2016 Drop Down Assets net income (1) 2,745 Combined net loss $ (52,182 ) (1) Results are fully reflected in SMLP's results of operations subsequent to closing the respective drop down.

CONDENSED CONSOLIDATING FINAN38

CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Condensed Balance Sheet	Balance sheets as of September 30, 2017 and December 31, 2016 follow. September 30, 2017 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Assets Cash and cash equivalents $ 492 $ 51 $ 1,528 $ 840 $ — $ 2,911 Accounts receivable 22 — 52,118 9,127 — 61,267 Other current assets 849 — 3,129 807 — 4,785 Due from affiliate — 16,354 488,170 3,392 (507,916 ) — Total current assets 1,363 16,405 544,945 14,166 (507,916 ) 68,963 Property, plant and equipment, net 4,424 — 1,459,053 421,092 — 1,884,569 Intangible assets, net — — 366,967 25,068 — 392,035 Goodwill — — 16,211 — — 16,211 Investment in equity method investees — — — 696,590 — 696,590 Other noncurrent assets 2,588 11,045 120 — — 13,753 Investment in subsidiaries 2,183,363 3,471,883 — — (5,655,246 ) — Total assets $ 2,191,738 $ 3,499,333 $ 2,387,296 $ 1,156,916 $ (6,163,162 ) $ 3,072,121 Liabilities and Partners' Capital Trade accounts payable $ 3,435 $ — $ 12,525 $ 6,716 $ — $ 22,676 Accrued expenses 1,385 — 11,302 1,428 — 14,115 Due to affiliate 508,430 — — — (507,916 ) 514 Deferred revenue — — 2,373 — — 2,373 Ad valorem taxes payable — — 7,687 431 — 8,118 Accrued interest — 20,183 — — — 20,183 Accrued environmental remediation — — — 5,089 — 5,089 Other current liabilities 4,779 — 3,582 602 — 8,963 Total current liabilities 518,029 20,183 37,469 14,266 (507,916 ) 82,031 Long-term debt — 1,295,787 — — — 1,295,787 Deferred Purchase Price Obligation 508,607 — — — — 508,607 Deferred revenue — — 15,421 — — 15,421 Noncurrent accrued environmental remediation — — — 1,429 — 1,429 Other noncurrent liabilities 3,794 — 3,561 183 — 7,538 Total liabilities 1,030,430 1,315,970 56,451 15,878 (507,916 ) 1,910,813 Total partners' capital 1,161,308 2,183,363 2,330,845 1,141,038 (5,655,246 ) 1,161,308 Total liabilities and partners' capital $ 2,191,738 $ 3,499,333 $ 2,387,296 $ 1,156,916 $ (6,163,162 ) $ 3,072,121 December 31, 2016 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Assets Cash and cash equivalents $ 698 $ 51 $ 5,647 $ 1,032 $ — $ 7,428 Accounts receivable 53 — 89,584 7,727 — 97,364 Other current assets 1,526 — 2,328 455 — 4,309 Due from affiliate 14,896 38,013 369,995 — (422,904 ) — Total current assets 17,173 38,064 467,554 9,214 (422,904 ) 109,101 Property, plant and equipment, net 2,266 — 1,440,180 411,225 — 1,853,671 Intangible assets, net — — 396,930 24,522 — 421,452 Goodwill — — 16,211 — — 16,211 Investment in equity method investees — — — 707,415 — 707,415 Other noncurrent assets 1,993 5,198 138 — — 7,329 Investment in subsidiaries 2,132,757 3,347,393 — — (5,480,150 ) — Total assets $ 2,154,189 $ 3,390,655 $ 2,321,013 $ 1,152,376 $ (5,903,054 ) $ 3,115,179 Liabilities and Partners' Capital Trade accounts payable $ 978 $ — $ 9,901 $ 5,372 $ — $ 16,251 Accrued expenses 2,399 114 6,069 2,807 — 11,389 Due to affiliate 408,266 — — 14,896 (422,904 ) 258 Ad valorem taxes payable 16 — 9,717 855 — 10,588 Accrued interest — 17,483 — — — 17,483 Accrued environmental remediation — — — 4,301 — 4,301 Other current liabilities 6,718 — 3,798 955 — 11,471 Total current liabilities 418,377 17,597 29,485 29,186 (422,904 ) 71,741 Long-term debt — 1,240,301 — — — 1,240,301 Deferred Purchase Price Obligation 563,281 — — — — 563,281 Deferred revenue — — 57,465 — — 57,465 Noncurrent accrued environmental remediation — — — 5,152 — 5,152 Other noncurrent liabilities 2,858 — 4,602 106 — 7,566 Total liabilities 984,516 1,257,898 91,552 34,444 (422,904 ) 1,945,506 Total partners' capital 1,169,673 2,132,757 2,229,461 1,117,932 (5,480,150 ) 1,169,673 Total liabilities and partners' capital $ 2,154,189 $ 3,390,655 $ 2,321,013 $ 1,152,376 $ (5,903,054 ) $ 3,115,179
Condensed Statement of Operations	Statements of operations for the three and nine months ended September 30, 2017 and 2016 follow. Three months ended September 30, 2017 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Revenues: Gathering services and related fees $ — $ — $ 79,546 $ 16,524 $ — $ 96,070 Natural gas, NGLs and condensate sales — — 22,828 112 — 22,940 Other revenues — — 5,202 733 — 5,935 Total revenues — — 107,576 17,369 — 124,945 Costs and expenses: Cost of natural gas and NGLs — — 18,115 62 — 18,177 Operation and maintenance — — 19,044 3,259 — 22,303 General and administrative — — 11,555 1,734 — 13,289 Depreciation and amortization 352 — 24,596 3,979 — 28,927 (Gain) loss on asset sales, net — — (82 ) 542 — 460 Long-lived asset impairment — — 696 594 — 1,290 Total costs and expenses 352 — 73,924 10,170 — 84,446 Other income 79 — — — — 79 Interest expense — (17,614 ) — — — (17,614 ) Deferred Purchase Price Obligation 70,499 — — — — 70,499 Income (loss) before income taxes and income from equity method investees 70,226 (17,614 ) 33,652 7,199 — 93,463 Income tax expense (176 ) — — — — (176 ) Income from equity method investees — — — 350 — 350 Equity in earnings of consolidated subsidiaries 23,587 41,201 — — (64,788 ) — Net income $ 93,637 $ 23,587 $ 33,652 $ 7,549 $ (64,788 ) $ 93,637 Three months ended September 30, 2016 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Revenues: Gathering services and related fees $ — $ — $ 64,065 $ 16,231 $ — $ 80,296 Natural gas, NGLs and condensate sales — — 9,578 — — 9,578 Other revenues — — 4,612 587 — 5,199 Total revenues — — 78,255 16,818 — 95,073 Costs and expenses: Cost of natural gas and NGLs — — 6,986 — — 6,986 Operation and maintenance — — 20,800 2,259 — 23,059 General and administrative — — 10,183 2,185 — 12,368 Depreciation and amortization 154 — 24,765 3,060 — 27,979 Loss on asset sales, net — — 13 — — 13 Long-lived asset impairment — — 1,172 — — 1,172 Total costs and expenses 154 — 63,919 7,504 — 71,577 Other income 51 — — — — 51 Interest expense — (15,733 ) — — — (15,733 ) Deferred Purchase Price Obligation (6,188 ) — — — — (6,188 ) (Loss) income before income taxes and income from equity method investees (6,291 ) (15,733 ) 14,336 9,314 — 1,626 Income tax benefit 142 — — — — 142 Income from equity method investees — — — 270 — 270 Equity in earnings of consolidated subsidiaries 8,187 23,920 — — (32,107 ) — Net income $ 2,038 $ 8,187 $ 14,336 $ 9,584 $ (32,107 ) $ 2,038 Nine months ended September 30, 2017 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Revenues: Gathering services and related fees $ — $ — $ 245,882 $ 53,002 $ — $ 298,884 Natural gas, NGLs and condensate sales — — 44,355 300 — 44,655 Other revenues — — 17,043 1,960 — 19,003 Total revenues — — 307,280 55,262 — 362,542 Costs and expenses: Cost of natural gas and NGLs — — 36,243 85 — 36,328 Operation and maintenance — — 60,812 9,199 — 70,011 General and administrative — — 34,317 6,053 — 40,370 Depreciation and amortization 660 — 73,817 11,707 — 86,184 Transaction costs 119 — — — — 119 Gain (loss) on asset sales, net — — (14 ) 544 — 530 Long-lived asset impairment — — 698 879 — 1,577 Total costs and expenses 779 — 205,873 28,467 — 235,119 Other income 214 — — — — 214 Interest expense — (51,883 ) — — — (51,883 ) Early extinguishment of debt — (22,020 ) — — — (22,020 ) Deferred Purchase Price Obligation 54,674 — — — — 54,674 Income (loss) before income taxes and loss from equity method investees 54,109 (73,903 ) 101,407 26,795 — 108,408 Income tax expense (417 ) — — — — (417 ) Loss from equity method investees — — — (3,691 ) — (3,691 ) Equity in earnings of consolidated subsidiaries 50,608 124,511 — — (175,119 ) — Net income $ 104,300 $ 50,608 $ 101,407 $ 23,104 $ (175,119 ) $ 104,300 Nine months ended September 30, 2016 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Revenues: Gathering services and related fees $ — $ — $ 191,510 $ 43,073 $ — $ 234,583 Natural gas, NGLs and condensate sales — — 25,747 — — 25,747 Other revenues — — 13,286 1,663 — 14,949 Total revenues — — 230,543 44,736 — 275,279 Costs and expenses: Cost of natural gas and NGLs — — 20,140 — — 20,140 Operation and maintenance — — 64,413 7,898 — 72,311 General and administrative — — 31,072 7,051 — 38,123 Depreciation and amortization 424 — 74,194 9,052 — 83,670 Transaction costs 1,296 — — — — 1,296 Loss on asset sales, net — — 24 — — 24 Long-lived asset impairment — — 1,212 529 — 1,741 Total costs and expenses 1,720 — 191,055 24,530 — 217,305 Other income 92 — — — — 92 Interest expense (1,441 ) (46,209 ) — — — (47,650 ) Deferred Purchase Price Obligation (31,116 ) — — — — (31,116 ) (Loss) income before income taxes and loss from equity method investees (34,185 ) (46,209 ) 39,488 20,206 — (20,700 ) Income tax expense (141 ) — — — — (141 ) Loss from equity method investees — — — (31,341 ) — (31,341 ) Equity in (loss) earnings of consolidated subsidiaries (17,856 ) 28,353 — — (10,497 ) — Net (loss) income $ (52,182 ) $ (17,856 ) $ 39,488 $ (11,135 ) $ (10,497 ) $ (52,182 )
Condensed Cash Flow Statement	Statements of cash flows for the nine months ended September 30, 2017 and 2016 follow. Nine months ended September 30, 2017 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Cash flows from operating activities: Net cash provided by (used in) operating activities $ 5,707 $ (45,854 ) $ 174,335 $ 62,309 $ — $ 196,497 Cash flows from investing activities: Capital expenditures (995 ) — (60,279 ) (24,932 ) — (86,206 ) Proceeds from asset sales — — — 2,300 — 2,300 Contributions to equity method investees — — — (21,581 ) — (21,581 ) Other, net (579 ) — — — — (579 ) Advances to affiliates 14,896 21,658 (118,175 ) (3,392 ) 85,013 — Net cash provided by (used in) investing activities 13,322 21,658 (178,454 ) (47,605 ) 85,013 (106,066 ) Cash flows from financing activities: Distributions to unitholders (134,066 ) — — — — (134,066 ) Borrowings under Revolving Credit Facility — 177,500 — — — 177,500 Repayments under Revolving Credit Facility — (319,500 ) — — — (319,500 ) Debt issuance costs — (15,891 ) — — — (15,891 ) Payment of redemption and call premiums on senior notes — (17,913 ) — — — (17,913 ) Proceeds from ATM Program issuances, net of costs 17,251 — — — — 17,251 Contribution from General Partner 465 — — — — 465 Issuance of senior notes — 500,000 — — — 500,000 Tender and redemption of senior notes — (300,000 ) — — — (300,000 ) Other, net (2,794 ) — — — — (2,794 ) Advances from affiliates 99,909 — — (14,896 ) (85,013 ) — Net cash (used in) provided by financing activities (19,235 ) 24,196 — (14,896 ) (85,013 ) (94,948 ) Net change in cash and cash equivalents (206 ) — (4,119 ) (192 ) — (4,517 ) Cash and cash equivalents, beginning of period 698 51 5,647 1,032 — 7,428 Cash and cash equivalents, end of period $ 492 $ 51 $ 1,528 $ 840 $ — $ 2,911 Nine months ended September 30, 2016 SMLP Co-Issuers Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating adjustments Total (In thousands) Cash flows from operating activities: Net cash provided by (used in) operating activities $ 3,740 $ (52,916 ) $ 159,650 $ 58,231 $ — $ 168,705 Cash flows from investing activities: Capital expenditures (904 ) — (39,630 ) (82,201 ) — (122,735 ) Contributions to equity method investees — — — (20,157 ) — (20,157 ) Acquisitions of gathering systems from affiliate (359,431 ) — — — — (359,431 ) Other, net (373 ) — — — — (373 ) Advances to affiliates (16,822 ) (245,093 ) (124,843 ) — 386,758 — Net cash used in investing activities (377,530 ) (245,093 ) (164,473 ) (102,358 ) 386,758 (502,696 ) Cash flows from financing activities: Distributions to unitholders (123,064 ) — — — — (123,064 ) Borrowings under Revolving Credit Facility 12,000 478,300 — — — 490,300 Repayments under Revolving Credit Facility — (189,300 ) — — — (189,300 ) Debt issuance costs — (3,013 ) — — — (3,013 ) Proceeds from issuance of common units, net 126,115 — — — — 126,115 Contribution from General Partner 2,702 — — — — 2,702 Cash advance from Summit Investments to contributed subsidiaries, net (12,000 ) — — 24,214 — 12,214 Expenses paid by Summit Investments on behalf of contributed subsidiaries 3,030 — — 1,791 — 4,821 Other, net (980 ) — — — — (980 ) Advances from affiliates 369,936 — — 16,822 (386,758 ) — Net cash provided by financing activities 377,739 285,987 — 42,827 (386,758 ) 319,795 Net change in cash and cash equivalents 3,949 (12,022 ) (4,823 ) (1,300 ) — (14,196 ) Cash and cash equivalents, beginning of period 73 12,407 6,930 2,383 — 21,793 Cash and cash equivalents, end of period $ 4,022 $ 385 $ 2,107 $ 1,083 $ — $ 7,597

ORGANIZATION, BUSINESS OPERAT39

ORGANIZATION, BUSINESS OPERATIONS AND PRESENTATION AND CONSOLIDATION - Narrative (Details) - shares	1 Months Ended	9 Months Ended
	Feb. 29, 2016	Sep. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Organization And Business Operations [Line Items]
Common limited partner capital (shares)		73,059,000	72,111,000
General Partner
Organization And Business Operations [Line Items]
General partner interest		2.00%
SMP Holdings | Contributed Entities
Organization And Business Operations [Line Items]
Percent of issued and outstanding membership interest	100.00%
SMP Holdings | OGC
Organization And Business Operations [Line Items]
Percentage of ownership interest	40.00%
Summit Investments | General Partner | Summit Midstream Partners, LP
Organization And Business Operations [Line Items]
General partner interest		2.00%
Subsidiary of Summit Investments
Organization And Business Operations [Line Items]
Ownership interest				1.00%
Common units | Energy Capital Partners
Organization And Business Operations [Line Items]
Common limited partner capital (shares)		5,915,827
Common units | SMP Holdings
Organization And Business Operations [Line Items]
Common limited partner capital (shares)		25,854,581

SUMMARY OF SIGNIFICANT ACCOUN40

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - Accounting Standards Update 2014-09 $ in Millions	Sep. 30, 2017USD ($)
Property, Plant and Equipment, Net | Contributions In Aid of Construction | Minimum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative expected impact upon adoption of new accounting principle	$ 30
Property, Plant and Equipment, Net | Contributions In Aid of Construction | Maximum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative expected impact upon adoption of new accounting principle	33
Partners Capital | Contributions In Aid of Construction | Minimum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative expected impact upon adoption of new accounting principle	8
Partners Capital | Contributions In Aid of Construction | Maximum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative expected impact upon adoption of new accounting principle	10
Partners Capital | Facility Fee | Minimum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative expected impact upon adoption of new accounting principle	(11)
Partners Capital | Facility Fee | Maximum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative expected impact upon adoption of new accounting principle	(13)
Deferred Revenue | Contributions In Aid of Construction | Minimum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative expected impact upon adoption of new accounting principle	22
Deferred Revenue | Contributions In Aid of Construction | Maximum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative expected impact upon adoption of new accounting principle	25
Deferred Revenue | Facility Fee | Minimum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative expected impact upon adoption of new accounting principle	11
Deferred Revenue | Facility Fee | Maximum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative expected impact upon adoption of new accounting principle	$ 13

SEGMENT INFORMATION - Assets, R

SEGMENT INFORMATION - Assets, Revenues, Depreciation and Amortization, and Capital Expenditures by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Assets	$ 3,072,121		$ 3,072,121		$ 3,115,179
Revenues	124,945	$ 95,073	362,542	$ 275,279
Depreciation and amortization	28,777	28,101	85,732	84,058
Capital expenditures			86,206	122,735
Reportable Segments
Segment Reporting Information [Line Items]
Assets	3,012,394		3,012,394		3,103,354
Revenues	116,277	95,073	353,014	275,279
Depreciation and amortization	28,425	27,947	85,072	83,633
Capital expenditures			53,809	121,831
Reportable Segments | Utica Shale
Segment Reporting Information [Line Items]
Assets	212,339		212,339		199,392
Revenues	9,727	7,665	28,979	17,351
Depreciation and amortization	1,818	961	5,213	2,756
Capital expenditures			21,425	72,036
Reportable Segments | Ohio Gathering
Segment Reporting Information [Line Items]
Assets	696,590		696,590		707,415
Reportable Segments | Williston Basin
Segment Reporting Information [Line Items]
Assets	695,120		695,120		724,084
Revenues	27,821	30,194	123,820	87,710
Depreciation and amortization	8,405	8,446	25,171	25,214
Capital expenditures			13,735	30,687
Reportable Segments | Piceance/DJ Basins
Segment Reporting Information [Line Items]
Assets	799,410		799,410		843,440
Revenues	53,875	31,076	122,446	89,479
Depreciation and amortization	12,199	12,273	36,635	36,843
Capital expenditures			17,902	15,421
Reportable Segments | Barnett Shale
Segment Reporting Information [Line Items]
Assets	389,026		389,026		404,314
Revenues	16,694	19,490	55,340	60,747
Depreciation and amortization	3,735	4,043	11,259	12,155
Capital expenditures			119	2,716
Reportable Segments | Marcellus Shale
Segment Reporting Information [Line Items]
Assets	219,909		219,909		224,709
Revenues	8,160	6,648	22,429	19,992
Depreciation and amortization	2,268	2,224	6,794	6,665
Capital expenditures			628	971
Corporate and other
Segment Reporting Information [Line Items]
Assets	60,699		60,699		12,294
Revenues	11,816	0	14,964	0
Depreciation and amortization	352	154	660	425
Capital expenditures			32,397	904
Corporate and other | Summit Permian
Segment Reporting Information [Line Items]
Capital expenditures			31,400
Eliminations
Segment Reporting Information [Line Items]
Assets	(972)		(972)		$ (469)
Revenues	$ (3,148)	$ 0	$ (5,436)	$ 0

SEGMENT INFORMATION - Concentra

SEGMENT INFORMATION - Concentration Risk (Details) - Revenue - Customer concentration	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Counterparty A - Piceance/DJ Basins
Segment Reporting Information [Line Items]
Concentration risk, percentage	17.00%	0.00%	0.00%	0.00%
Counterparty B - Williston Basin
Segment Reporting Information [Line Items]
Concentration risk, percentage	0.00%	0.00%	16.00%	0.00%
Counterparty C - Piceance/DJ Basins
Segment Reporting Information [Line Items]
Concentration risk, percentage	0.00%	10.00%	0.00%	0.00%

SEGMENT INFORMATION - Adjusted

SEGMENT INFORMATION - Adjusted EBITDA by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 82,674	$ 85,205	$ 246,189	$ 245,608
Utica Shale
Segment Reporting Information [Line Items]
Adjusted EBITDA	8,412	6,983	25,857	14,898
Ohio Gathering
Segment Reporting Information [Line Items]
Adjusted EBITDA	10,522	10,059	29,201	35,173
Williston Basin
Segment Reporting Information [Line Items]
Adjusted EBITDA	16,212	21,815	51,176	60,745
Piceance/DJ Basins
Segment Reporting Information [Line Items]
Adjusted EBITDA	30,008	28,074	86,256	79,120
Barnett Shale
Segment Reporting Information [Line Items]
Adjusted EBITDA	10,838	13,128	35,924	41,118
Marcellus Shale
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 6,682	$ 5,146	$ 17,775	$ 14,554

SEGMENT INFORMATION - Reconcili

SEGMENT INFORMATION - Reconciliation of Net Income to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting [Abstract]
Income (loss) before income taxes and income (loss) from equity method investees	$ 93,463	$ 1,626	$ 108,408	$ (20,700)
Add:
Corporate and other	9,197	8,722	28,725	26,728
Interest expense	17,614	15,733	51,883	47,650
Early extinguishment of debt	0	0	22,020	0
Deferred Purchase Price Obligation	(70,499)	6,188	(54,674)	31,116
Depreciation and amortization	28,777	28,101	85,732	84,058
Proportional adjusted EBITDA for equity method investees	10,522	10,059	29,201	35,173
Adjustments related to MVC shortfall payments	(10,124)	11,541	(33,186)	33,818
Unit-based and noncash compensation	1,974	2,050	5,973	6,000
Loss on asset sales, net	460	13	530	24
Long-lived asset impairment	1,290	1,172	1,577	1,741
Total of reportable segments' measures of profit or loss	$ 82,674	$ 85,205	$ 246,189	$ 245,608

SEGMENT INFORMATION - Schedule

SEGMENT INFORMATION - Schedule of Adjustments Related to Minimum Volume Commitments Shortfall Payments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Net change in deferred revenue for MVC shortfall payments	$ 0	$ 847	$ (39,671)	$ 2,879
Expected MVC shortfall adjustments	(10,124)	10,694	6,485	30,939
Total adjustments related to MVC shortfall payments	(10,124)	11,541	(33,186)	33,818
Williston Basin
Segment Reporting Information [Line Items]
Net change in deferred revenue for MVC shortfall payments	0	0	(37,693)	235
Expected MVC shortfall adjustments	1,982	4,195	5,946	11,757
Total adjustments related to MVC shortfall payments	1,982	4,195	(31,747)	11,992
Piceance/DJ Basins
Segment Reporting Information [Line Items]
Net change in deferred revenue for MVC shortfall payments	0	847	(1,978)	3,321
Expected MVC shortfall adjustments	(12,200)	6,412	867	18,911
Total adjustments related to MVC shortfall payments	(12,200)	7,259	(1,111)	22,232
Barnett Shale
Segment Reporting Information [Line Items]
Net change in deferred revenue for MVC shortfall payments	0	0	0	(677)
Expected MVC shortfall adjustments	94	87	(328)	271
Total adjustments related to MVC shortfall payments	$ 94	$ 87	$ (328)	$ (406)

PROPERTY, PLANT AND EQUIPMENT46

PROPERTY, PLANT AND EQUIPMENT, NET (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 2,197,933		$ 2,197,933		$ 2,112,986
Less accumulated depreciation	313,364		313,364		259,315
Property, plant and equipment, net	1,884,569		1,884,569		1,853,671
Depreciation expense	18,837	$ 17,609	55,935	$ 52,574
Capitalized interest	644	$ 1,354	1,562	$ 3,133
Gathering and processing systems and related equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,075,327		2,075,327		2,026,363
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	71,196		71,196		39,954
Land and line fill
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	11,735		11,735		11,442
Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 39,675		$ 39,675		$ 35,227

AMORTIZING INTANGIBLE ASSETS 47

AMORTIZING INTANGIBLE ASSETS AND UNFAVORABLE GAS GATHERING CONTRACT - Intangible assets and liabilities subject to amortization (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 605,674	$ 603,674
Accumulated amortization	(213,639)	(182,222)
Net	$ 392,035	$ 421,452
Unfavorable gas gathering contract
Useful lives (In years)	10 years	10 years
Gross carrying amount	$ 10,962	$ 10,962
Accumulated amortization	(8,535)	(6,916)
Net	$ 2,427	$ 4,046
Favorable gas gathering contracts
Finite-Lived Intangible Assets [Line Items]
Useful lives (In years)	18 years 8 months 12 days	18 years 8 months 12 days
Gross carrying amount	$ 24,195	$ 24,195
Accumulated amortization	(11,962)	(10,795)
Net	$ 12,233	$ 13,400
Contract intangibles
Finite-Lived Intangible Assets [Line Items]
Useful lives (In years)	12 years 6 months	12 years 6 months
Gross carrying amount	$ 426,464	$ 426,464
Accumulated amortization	(172,120)	(146,468)
Net	$ 254,344	$ 279,996
Rights-of-way
Finite-Lived Intangible Assets [Line Items]
Useful lives (In years)	26 years 1 month 6 days	26 years 1 month 6 days
Gross carrying amount	$ 155,015	$ 153,015
Accumulated amortization	(29,557)	(24,959)
Net	$ 125,458	$ 128,056

AMORTIZING INTANGIBLE ASSETS 48

AMORTIZING INTANGIBLE ASSETS AND UNFAVORABLE GAS GATHERING CONTRACT - Recognized amortization expense in other revenues and cost and expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other revenue | Favorable gas gathering contracts
Amortization expense
Amortization expense	$ (390)	$ (289)	$ (1,167)	$ (944)
Other revenue | Unfavorable gas gathering contract
Amortization expense
Amortization expense	540	167	1,619	556
Costs and expenses | Contract intangibles
Amortization expense
Amortization expense	8,550	8,854	25,652	26,562
Costs and expenses | Rights-of-way
Amortization expense
Amortization expense	$ 1,540	$ 1,517	$ 4,597	$ 4,534

AMORTIZING INTANGIBLE ASSETS 49

AMORTIZING INTANGIBLE ASSETS AND UNFAVORABLE GAS GATHERING CONTRACT - Estimated aggregate annual amortization expected to be recognized (Details) $ in Thousands	Sep. 30, 2017USD ($)
Intangible assets
2,017	$ 10,480
2,018	41,392
2,019	41,223
2,020	43,470
2,021	41,698
Unfavorable gas gathering contract
2,017	539
2,018	1,888
2,019	0
2,020	0
2,021	$ 0

GOODWILL (Details)

GOODWILL (Details)	9 Months Ended
	Sep. 30, 2017USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill impairment	$ 0

EQUITY METHOD INVESTMENTS - Rol

EQUITY METHOD INVESTMENTS - Rollforward of the Investment in Equity Method Investees (Details) - USD ($) $ in Thousands	1 Months Ended			9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Equity Method Investment [Roll Forward]
Investment in equity method investees, September 30, 2017	$ 696,590			$ 696,590
Distributions from equity method investees				28,715	$ 34,139
Investment in equity method investees, net of basis difference, August 31, 2017				707,415
OGC | Summit Midstream Partners, LLC
Equity Method Investment [Roll Forward]
Investment in equity method investees, September 30, 2017	696,590			696,590
Distributions from equity method investees	4,360
Basis difference	(133,522)
Investment in equity method investees, net of basis difference, August 31, 2017	$ 567,428
OGC and OCC
Equity Method Investment [Roll Forward]
Impairment loss				$ 8,700	$ 94,400
Principal Owner | OGC
Schedule of Equity Method Investments [Line Items]
Equity method potential ownership interest percent		40.00%	40.00%
Equity Method Investment [Roll Forward]
Impairment loss		$ 3,500	$ 37,800
Ownership percent	40.00%			40.00%

EQUITY METHOD INVESTMENTS - Sta

EQUITY METHOD INVESTMENTS - Statements of Operations Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2017	Aug. 31, 2016
OGC
Schedule of Equity Method Investments [Line Items]
Total revenues	$ 35,144	$ 34,018	$ 103,302	$ 110,261
Total operating expenses	25,720	24,189	86,046	69,294
Net income (loss)	9,424	9,825	17,258	40,962
OCC
Schedule of Equity Method Investments [Line Items]
Total revenues	1,814	3,478	5,871	14,093
Total operating expenses	1,877	5,092	6,186	108,399
Net income (loss)	$ (204)	$ (806)	$ (1,396)	$ (94,051)

DEFERRED REVENUE - Rollforward

DEFERRED REVENUE - Rollforward of deferred revenue (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	$ 0
Current deferred revenue, Additions	13,584
Current deferred revenue, Less revenue recognized	11,211
Current deferred revenue, ending balance	2,373
Noncurrent deferred revenue, beginning balance	57,465
Less revenue recognized	39,671
Less reclassification to current deferred revenue	2,373
Noncurrent deferred revenue, ending balance	15,421
Williston Basin
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	0
Current deferred revenue, Additions	0
Current deferred revenue, Less revenue recognized	0
Current deferred revenue, ending balance	0
Noncurrent deferred revenue, beginning balance	37,693
Less revenue recognized	37,693
Less reclassification to current deferred revenue	0
Noncurrent deferred revenue, ending balance	0
Piceance/DJ Basins
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	0
Current deferred revenue, Additions	0
Current deferred revenue, Less revenue recognized	11,211
Current deferred revenue, ending balance	2,373
Noncurrent deferred revenue, beginning balance	19,772
Less revenue recognized	1,978
Less reclassification to current deferred revenue	2,373
Noncurrent deferred revenue, ending balance	$ 15,421

DEFERRED REVENUE - Narrative (D

DEFERRED REVENUE - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Sep. 30, 2017
Deferred Revenue Arrangement [Line Items]
Accounts receivable potentially used to offset fees		$ 0
Piceance/DJ Basins | Gathering Services and Related Fees
Deferred Revenue Arrangement [Line Items]
Recognized amount of deferred revenue	$ 37,700,000
Accrued Income Receivable
Deferred Revenue Arrangement [Line Items]
Shortfall payment billings included in accounts receivable		$ 8,600,000

DEBT - Components of Long-Term

DEBT - Components of Long-Term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Total long-term debt	$ 1,295,787	$ 1,240,301
SMP Holdings
Line of Credit Facility [Line Items]
Total long-term debt	1,295,787	1,240,301
SMP Holdings | Senior Unsecured Notes Due August 2022
Line of Credit Facility [Line Items]
Unsecured notes	300,000	300,000
Less unamortized debt issuance costs	(3,049)	(3,516)
SMP Holdings | Senior Unsecured Notes Due August 2025
Line of Credit Facility [Line Items]
Unsecured notes	500,000	0
Less unamortized debt issuance costs	(7,164)	0
SMP Holdings | Senior Unsecured Notes Due March 2017
Line of Credit Facility [Line Items]
Unsecured notes	0	300,000
Less unamortized debt issuance costs	0	(4,183)
SMP Holdings | Revolving Credit Facility
Line of Credit Facility [Line Items]
Revolving credit facility	$ 506,000	$ 648,000

DEBT - Components of Long-Ter56

DEBT - Components of Long-Term Debt (Parenthetical) (Details)	Sep. 30, 2017	Dec. 31, 2016
Revolving Credit Facility
Line of Credit Facility [Line Items]
Variable interest rate	3.74%
SMP Holdings | Senior Unsecured Notes Due August 2022
Line of Credit Facility [Line Items]
Stated interest rate	5.50%	5.50%
SMP Holdings | Senior Unsecured Notes Due August 2025
Line of Credit Facility [Line Items]
Stated interest rate	5.75%
SMP Holdings | Senior Unsecured Notes Due March 2017
Line of Credit Facility [Line Items]
Stated interest rate		7.50%
SMP Holdings | Revolving Credit Facility
Line of Credit Facility [Line Items]
Variable interest rate	3.74%	3.27%

DEBT - Maturities (Details)

DEBT - Maturities (Details) $ in Thousands	Sep. 30, 2017USD ($)
Debt Disclosure [Abstract]
2,017	$ 0
2,018	0
2,019	0
2,020	0
2,021	0
Thereafter	1,306,000
Total long-term debt	$ 1,306,000

DEBT - Revolving Credit Facilit

DEBT - Revolving Credit Facility (Details)	9 Months Ended
	Sep. 30, 2017USD ($)	May 26, 2017	May 25, 2017
Line of Credit Facility [Line Items]
Debt issuance costs	$ 8,100,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowing capacity	1,250,000,000
Accordion feature	$ 250,000,000
Leverage ratio		5.50	5
Senior secured leverage ratio	3.75
Commitment fee on unused portion of the facility	0.50%
Interest rate at period end	3.74%
Unused portion under the facility	$ 744,000,000
Cumulative payment obligations, maximum	50,000,000
Debt issuance costs	11,100,000
Debt defaults	$ 0
Revolving Credit Facility | LIBOR
Line of Credit Facility [Line Items]
Applicable margin	2.50%
Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Commitment fee on unused portion of the facility	0.30%
Ratio of consolidated trailing 12-month EBITDA to net interest expense	2.5
Revolving Credit Facility | Minimum | ABR
Line of Credit Facility [Line Items]
Applicable margin	0.75%
Revolving Credit Facility | Minimum | LIBOR
Line of Credit Facility [Line Items]
Applicable margin	1.75%
Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Commitment fee on unused portion of the facility	0.50%
Ratio of total net indebtedness to consolidated trailing 12-month EBITDA	5.50
Ratio of first lien net indebtedness to consolidated trailing 12-month EBITDA	3.75
Revolving Credit Facility | Maximum | ABR
Line of Credit Facility [Line Items]
Applicable margin	1.75%
Revolving Credit Facility | Maximum | LIBOR
Line of Credit Facility [Line Items]
Applicable margin	2.75%

DEBT - Senior Notes (Details)

DEBT - Senior Notes (Details) - USD ($)	Feb. 16, 2017	Feb. 14, 2017	Feb. 28, 2017	Jun. 30, 2013	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Feb. 08, 2017	Dec. 31, 2016	Jul. 31, 2014
Debt Instrument [Line Items]
Early extinguishment of debt						$ 302,000	$ 0
Revolving Credit Facility
Debt Instrument [Line Items]
Extinguishment of debt			$ 172,000,000
7.5% Senior Notes
Debt Instrument [Line Items]
Stated interest rate									7.50%
Debt face amount									$ 300,000,000
5.75% Senior Notes
Debt Instrument [Line Items]
Stated interest rate								5.75%
Debt face amount								$ 500,000,000
Deferred issuance costs								$ 7,800
Default period			30 days
Compliance notice period			30 days
Final judgment			$ 75,000,000
Percent of principal (at least)			25.00%
5.75% Senior Notes | Redemption period one
Debt Instrument [Line Items]
Percent of principal redeemed			35.00%
Redemption price, expressed as percentage of principal amount			105.75%
5.75% Senior Notes | Redemption period two
Debt Instrument [Line Items]
Redemption price, expressed as percentage of principal amount			104.313%
5.75% Senior Notes | Redemption period three
Debt Instrument [Line Items]
Redemption price, expressed as percentage of principal amount			100.00%
Summit Holdings and Finance Corporation | 7.5% Senior Notes
Debt Instrument [Line Items]
Senior unsecured notes				$ 300,000,000
Stated interest rate				7.50%
Extinguishment of debt	$ 23,100,000	$ 276,900,000
Redemption and call premiums			$ 17,900,000		$ (17,900,000)
Early extinguishment of debt					$ 4,100,000
Summit Holdings and Finance Corporation | 5.5% Senior Notes
Debt Instrument [Line Items]
Senior unsecured notes										$ 300,000,000
Stated interest rate										5.50%
Finance Corp | Summit Holdings
Debt Instrument [Line Items]
Cumulative percentage ownership in subsidiary				100.00%

DEBT - SMP Holdings Credit Faci

DEBT - SMP Holdings Credit Facility (Details) - USD ($)	Sep. 30, 2017	Jun. 30, 2017
Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing capacity	$ 1,250,000,000
SMP Holdings | Term Loan Credit Facility
Debt Instrument [Line Items]
Debt face amount		$ 200,000,000
SMP Holdings | Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing capacity		$ 250,000,000

FINANCIAL INSTRUMENTS - Concent

FINANCIAL INSTRUMENTS - Concentration Risk - Narrative (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Five Largest Customers | Accounts receivable | Customer concentration
CONCENTRATIONS OF RISK
Concentration risk, percentage	41.00%	62.00%

FINANCIAL INSTRUMENTS - Liabili

FINANCIAL INSTRUMENTS - Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation (Details) - Fair Value, Inputs, Level 3 $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Level 3 liability, January 1, 2017	$ 563,281
Change in fair value	(54,674)
Level 3 liability, September 30, 2017	$ 508,607

FINANCIAL INSTRUMENTS - Fair va

FINANCIAL INSTRUMENTS - Fair value of Debt Instruments (Details) - Summit Holdings - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Carrying value | Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revolving credit facility	$ 506,000	$ 648,000
Carrying value | 5.5% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	296,951	296,484
Carrying value | 5.75% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	492,836
Carrying value | 7.5% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes		295,817
Fair Value | Revolving Credit Facility | Estimated fair value (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revolving credit facility	506,000	648,000
Fair Value | 5.5% Senior Notes | Estimated fair value (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	301,625	294,500
Fair Value | 5.75% Senior Notes | Estimated fair value (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 506,875
Fair Value | 7.5% Senior Notes | Estimated fair value (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes		$ 316,000

FINANCIAL INSTRUMENTS - Fair 64

FINANCIAL INSTRUMENTS - Fair value of Debt Instruments (Parenthetical) (Details) - Summit Holdings - Senior Notes - USD ($)	Sep. 30, 2017	Dec. 31, 2016
5.5% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	5.50%	5.50%
Debt face amount	$ 300,000,000	$ 300,000,000
5.75% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	5.75%
Debt face amount	$ 500,000,000
7.5% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate		7.50%
Debt face amount		$ 300,000,000

PARTNERS' CAPITAL - Partners' C

PARTNERS' CAPITAL - Partners' Capital and Schedule of Units (Details)	9 Months Ended
	Sep. 30, 2017shares
Rollforward of the number of partner units
Units, beginning balance (in shares)	73,582,308,000
Net units issued under SMLP LTIP (in shares)	184,277,000
Units issued under ATM program (in shares)	763,548,000
General Partner 2% contribution	19,812,000
Units, ending balance (in shares)	74,549,945,000
Common
Rollforward of the number of partner units
Units, beginning balance (in shares)	72,111,121,000
Net units issued under SMLP LTIP (in shares)	184,277,000
Units issued under ATM program (in shares)	763,548,000
General Partner 2% contribution	0
Units, ending balance (in shares)	73,058,946,000
General Partner
Rollforward of the number of partner units
Units, beginning balance (in shares)	1,471,187,000
Net units issued under SMLP LTIP (in shares)	0
Units issued under ATM program (in shares)	0
General Partner 2% contribution	19,812,000
Units, ending balance (in shares)	1,490,999,000

PARTNERS' CAPITAL - Partners'66

PARTNERS' CAPITAL - Partners' Capital and Schedule of Units (Parenthetical) (Details)	9 Months Ended
	Sep. 30, 2017
General Partner
Rollforward of the number of partner units
General partner interest	2.00%

PARTNERS' CAPITAL - Narrative (

PARTNERS' CAPITAL - Narrative (Details) $ / shares in Units, $ in Thousands	Nov. 13, 2017USD ($)	Oct. 26, 2017$ / shares	Feb. 28, 2017USD ($)shares	Sep. 30, 2017USD ($)$ / sharesshares	Sep. 30, 2016$ / shares	Sep. 30, 2017USD ($)ATM$ / sharesshares	Sep. 30, 2016USD ($)$ / shares
Class of Stock [Line Items]
Units issued under ATM program (in shares) | shares						763,548,000
Aggregate gross proceeds						$ 17,251	$ 0
Per-unit annual distributions to unitholders (in dollars per unit) | $ / shares				$ 0.575	$ 0.575	$ 1.725	$ 1.725
Surplus in excess (in dollars per share) | $ / shares						$ 0.46
Subsequent Event
Class of Stock [Line Items]
Per-unit annual distributions to unitholders (in dollars per unit) | $ / shares		$ 0.575
Cash paid to unit holders	$ 45,000
Common
Class of Stock [Line Items]
Units issued under ATM program (in shares) | shares						763,548,000
Common | Public Offering
Class of Stock [Line Items]
Units issued under ATM program (in shares) | shares			4,000,000
Aggregate offering price			$ 150,000
Amount of stock sold (in shares) | shares				0		763,548
Aggregate gross proceeds						$ 17,700
Compensation paid to sales agents						200
Aggregate offering price				$ 132,300		$ 132,300
Transactions under ATM Program | ATM						0
General Partner
Class of Stock [Line Items]
Percentage interest in distributions (maximum)						50.00%

PARTNERS' CAPITAL - Cash Distri

PARTNERS' CAPITAL - Cash Distributions Paid and Declared (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Equity [Abstract]
Per-unit annual distributions to unitholders (in dollars per unit)	$ 0.575	$ 0.575	$ 1.725	$ 1.725

PARTNERS' CAPITAL - Incentive D

PARTNERS' CAPITAL - Incentive Distribution Rights (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Equity [Abstract]
IDR payments	$ 2,127	$ 1,938	$ 6,333	$ 5,811

EARNINGS PER UNIT (Details)

EARNINGS PER UNIT (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator for basic and diluted EPU:
Net income (loss) attributable to limited partners	$ 89,547	$ (215)	$ 95,576	$ (59,702)
Common units
Denominator for basic and diluted EPU:
Weighted-average common units outstanding – basic	73,059	67,844	72,583	66,978
Effect of nonvested phantom units (in shares)	374	0	318	0
Weighted-average common units outstanding – diluted (shares)	73,433	67,844	72,901	66,978
Earnings (loss) per limited partner unit:
Common unit - basic (USD per share)	$ 1.23	$ 0	$ 1.32	$ (0.89)
Common unit - diluted (USD per share)	$ 1.22	$ 0	$ 1.31	$ (0.89)
Phantom Units
Earnings (loss) per limited partner unit:
Nonvested anti-dilutive phantom units excluded from the calculation of diluted EPU (in shares)	0	0	55	167

UNIT-BASED AND NONCASH COMPEN71

UNIT-BASED AND NONCASH COMPENSATION (Details) - SMLP LTIP - $ / shares	1 Months Ended
	Mar. 31, 2017	Sep. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Units remaining available (in shares)		3,600,000
Phantom Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted units (in shares)	366,181
Grant date fair value (in dollars per share)	$ 22.50
Vesting period (years)	3 years
Units vested (in shares)	184,277

RELATED-PARTY TRANSACTIONS - Ex

RELATED-PARTY TRANSACTIONS - Expenses Incurred by the General Partner and Reimbursed (Details) - General Partner - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operation and maintenance expense
RELATED-PARTY TRANSACTIONS
Expenses from transactions with related party	$ 6,792	$ 6,689	$ 20,404	$ 20,061
General and administrative expense
RELATED-PARTY TRANSACTIONS
Expenses from transactions with related party	$ 6,840	$ 7,761	$ 23,030	$ 23,218

RELATED-PARTY TRANSACTIONS - Na

RELATED-PARTY TRANSACTIONS - Narrative (Details) - SMP Holdings	1 Months Ended
	Feb. 28, 2017$ / sharesshares
RELATED-PARTY TRANSACTIONS
Shares sold (in shares) | shares	4,000,000
Sale price (in dollars per share) | $ / shares	$ 24

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Rent Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Commitments And Contingencies Disclosure [Abstract]
Rent expense	$ 1,009	$ 754	$ 2,811	$ 2,115

COMMITMENTS AND CONTINGENCIES75

COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended	12 Months Ended
	Jan. 31, 2017	Sep. 30, 2017	Dec. 31, 2015
Maximum | Meadowlark Midstream Gathering System | Principal Owner
Loss Contingencies [Line Items]
Coverage from pollution liability insurance policy		$ 25	$ 25
Coverage from property and business interruption insurance policy		$ 200
Business Interruption
Loss Contingencies [Line Items]
Recoveries recognized	$ 2.6
Property Recoveries
Loss Contingencies [Line Items]
Recoveries recognized	$ 0.4

COMMITMENTS AND CONTINGENCIES76

COMMITMENTS AND CONTINGENCIES - Environmental Matters (Details) - Meadowlark Midstream Gathering System $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Accrual for Environmental Loss Contingencies [Roll Forward]
Accrued environmental remediation, beginning balance	$ 9,453
Payments made	(2,935)
Accrued environmental remediation, ending balance	$ 6,518

ACQUISITIONS AND DROP DOWN TR77

ACQUISITIONS AND DROP DOWN TRANSACTIONS - 2016 Drop Down (Details) $ in Thousands	Mar. 03, 2016USD ($)	Jun. 30, 2016USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2016USD ($)
Business Acquisition [Line Items]
Deferred purchase price obligation			$ 508,607	$ 563,281
Drop Down Assets 2016 Acquisition
Business Acquisition [Line Items]
Initial payment	$ 360,000
Working capital adjustment		$ 600
Deferred Purchase price obligation, multiple	6.5
Estimated future payment obligation	$ 860,300		656,500
Deferred purchase price obligation	$ 507,400		$ 508,600
Discount rate	13.00%		10.75%

ACQUISITIONS AND DROP DOWN TR78

ACQUISITIONS AND DROP DOWN TRANSACTIONS - Revenue and Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Combined revenues	$ 124,945	$ 95,073	$ 362,542	$ 275,279
Combined net loss	$ 93,637	$ 2,038	$ 104,300	(52,182)
Summit Midstream Partners, LP
Business Acquisition [Line Items]
Combined revenues				266,412
Combined net loss				(54,927)
Drop Down Assets 2016 Acquisition
Business Acquisition [Line Items]
Combined revenues				8,867
Combined net loss				$ 2,745

CONDENSED CONSOLIDATING FINAN79

CONDENSED CONSOLIDATING FINANCIAL INFORMATION - Condensed Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Assets
Cash and cash equivalents	$ 2,911	$ 7,428	$ 7,597	$ 21,793
Accounts receivable	61,267	97,364
Other current assets	4,785	4,309
Due from affiliate	0	0
Total current assets	68,963	109,101
Property, plant and equipment, net	1,884,569	1,853,671
Intangible assets, net	392,035	421,452
Goodwill	16,211	16,211
Investment in equity method investees	696,590	707,415
Other noncurrent assets	13,753	7,329
Investment in subsidiaries	0	0
Total assets	3,072,121	3,115,179
Liabilities and Partners' Capital
Trade accounts payable	22,676	16,251
Accrued expenses	14,115	11,389
Due to affiliate	514	258
Deferred revenue	2,373	0
Ad valorem taxes payable	8,118	10,588
Accrued interest	20,183	17,483
Accrued environmental remediation	5,089	4,301
Other current liabilities	8,963	11,471
Total current liabilities	82,031	71,741
Long-term debt	1,295,787	1,240,301
Deferred Purchase Price Obligation	508,607	563,281
Deferred revenue	15,421	57,465
Noncurrent accrued environmental remediation	1,429	5,152
Other noncurrent liabilities	7,538	7,566
Total liabilities	1,910,813	1,945,506
Total partners' capital	1,161,308	1,169,673	1,199,400	1,747,299
Total liabilities and partners' capital	3,072,121	3,115,179
Consolidating adjustments
Assets
Cash and cash equivalents	0	0	0	0
Accounts receivable	0	0
Other current assets	0	0
Due from affiliate	(507,916)	(422,904)
Total current assets	(507,916)	(422,904)
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	(5,655,246)	(5,480,150)
Total assets	(6,163,162)	(5,903,054)
Liabilities and Partners' Capital
Trade accounts payable	0	0
Accrued expenses	0	0
Due to affiliate	(507,916)	(422,904)
Deferred revenue	0
Ad valorem taxes payable	0	0
Accrued interest	0	0
Accrued environmental remediation	0	0
Other current liabilities	0	0
Total current liabilities	(507,916)	(422,904)
Long-term debt	0	0
Deferred Purchase Price Obligation	0	0
Deferred revenue	0	0
Noncurrent accrued environmental remediation	0	0
Other noncurrent liabilities	0	0
Total liabilities	(507,916)	(422,904)
Total partners' capital	(5,655,246)	(5,480,150)
Total liabilities and partners' capital	(6,163,162)	(5,903,054)
Summit Midstream Partners, LP | Reportable Legal Entities
Assets
Cash and cash equivalents	492	698	4,022	73
Accounts receivable	22	53
Other current assets	849	1,526
Due from affiliate	0	14,896
Total current assets	1,363	17,173
Property, plant and equipment, net	4,424	2,266
Intangible assets, net	0	0
Goodwill	0	0
Investment in equity method investees	0	0
Other noncurrent assets	2,588	1,993
Investment in subsidiaries	2,183,363	2,132,757
Total assets	2,191,738	2,154,189
Liabilities and Partners' Capital
Trade accounts payable	3,435	978
Accrued expenses	1,385	2,399
Due to affiliate	508,430	408,266
Deferred revenue	0
Ad valorem taxes payable	0	16
Accrued interest	0	0
Accrued environmental remediation	0	0
Other current liabilities	4,779	6,718
Total current liabilities	518,029	418,377
Long-term debt	0	0
Deferred Purchase Price Obligation	508,607	563,281
Deferred revenue	0	0
Noncurrent accrued environmental remediation	0	0
Other noncurrent liabilities	3,794	2,858
Total liabilities	1,030,430	984,516
Total partners' capital	1,161,308	1,169,673
Total liabilities and partners' capital	2,191,738	2,154,189
Co-Issuers | Reportable Legal Entities
Assets
Cash and cash equivalents	51	51	385	12,407
Accounts receivable	0	0
Other current assets	0	0
Due from affiliate	16,354	38,013
Total current assets	16,405	38,064
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	11,045	5,198
Investment in subsidiaries	3,471,883	3,347,393
Total assets	3,499,333	3,390,655
Liabilities and Partners' Capital
Trade accounts payable	0	0
Accrued expenses	0	114
Due to affiliate	0	0
Deferred revenue	0
Ad valorem taxes payable	0	0
Accrued interest	20,183	17,483
Accrued environmental remediation	0	0
Other current liabilities	0	0
Total current liabilities	20,183	17,597
Long-term debt	1,295,787	1,240,301
Deferred Purchase Price Obligation	0	0
Deferred revenue	0	0
Noncurrent accrued environmental remediation	0	0
Other noncurrent liabilities	0	0
Total liabilities	1,315,970	1,257,898
Total partners' capital	2,183,363	2,132,757
Total liabilities and partners' capital	3,499,333	3,390,655
Guarantor Subsidiaries | Reportable Legal Entities
Assets
Cash and cash equivalents	1,528	5,647	2,107	6,930
Accounts receivable	52,118	89,584
Other current assets	3,129	2,328
Due from affiliate	488,170	369,995
Total current assets	544,945	467,554
Property, plant and equipment, net	1,459,053	1,440,180
Intangible assets, net	366,967	396,930
Goodwill	16,211	16,211
Investment in equity method investees	0	0
Other noncurrent assets	120	138
Investment in subsidiaries	0	0
Total assets	2,387,296	2,321,013
Liabilities and Partners' Capital
Trade accounts payable	12,525	9,901
Accrued expenses	11,302	6,069
Due to affiliate	0	0
Deferred revenue	2,373
Ad valorem taxes payable	7,687	9,717
Accrued interest	0	0
Accrued environmental remediation	0	0
Other current liabilities	3,582	3,798
Total current liabilities	37,469	29,485
Long-term debt	0	0
Deferred Purchase Price Obligation	0	0
Deferred revenue	15,421	57,465
Noncurrent accrued environmental remediation	0	0
Other noncurrent liabilities	3,561	4,602
Total liabilities	56,451	91,552
Total partners' capital	2,330,845	2,229,461
Total liabilities and partners' capital	2,387,296	2,321,013
Non-Guarantor Subsidiaries | Reportable Legal Entities
Assets
Cash and cash equivalents	840	1,032	$ 1,083	$ 2,383
Accounts receivable	9,127	7,727
Other current assets	807	455
Due from affiliate	3,392	0
Total current assets	14,166	9,214
Property, plant and equipment, net	421,092	411,225
Intangible assets, net	25,068	24,522
Goodwill	0	0
Investment in equity method investees	696,590	707,415
Other noncurrent assets	0	0
Investment in subsidiaries	0	0
Total assets	1,156,916	1,152,376
Liabilities and Partners' Capital
Trade accounts payable	6,716	5,372
Accrued expenses	1,428	2,807
Due to affiliate	0	14,896
Deferred revenue	0
Ad valorem taxes payable	431	855
Accrued interest	0	0
Accrued environmental remediation	5,089	4,301
Other current liabilities	602	955
Total current liabilities	14,266	29,186
Long-term debt	0	0
Deferred Purchase Price Obligation	0	0
Deferred revenue	0	0
Noncurrent accrued environmental remediation	1,429	5,152
Other noncurrent liabilities	183	106
Total liabilities	15,878	34,444
Total partners' capital	1,141,038	1,117,932
Total liabilities and partners' capital	$ 1,156,916	$ 1,152,376

CONDENSED CONSOLIDATING FINAN80

CONDENSED CONSOLIDATING FINANCIAL INFORMATION - Condensed Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Gathering services and related fees	$ 96,070	$ 80,296	$ 298,884	$ 234,583
Natural gas, NGLs and condensate sales	22,940	9,578	44,655	25,747
Other revenues	5,935	5,199	19,003	14,949
Total revenues	124,945	95,073	362,542	275,279
Costs and expenses:
Cost of natural gas and NGLs	18,177	6,986	36,328	20,140
Operation and maintenance	22,303	23,059	70,011	72,311
General and administrative	13,289	12,368	40,370	38,123
Transaction costs	0	0	119	1,296
Depreciation and amortization	28,927	27,979	86,184	83,670
Loss on asset sales, net	460	13	530	24
Long-lived asset impairment	1,290	1,172	1,577	1,741
Total costs and expenses	84,446	71,577	235,119	217,305
Other income	79	51	214	92
Interest expense	(17,614)	(15,733)	(51,883)	(47,650)
Early extinguishment of debt	0	0	(22,020)	0
Deferred Purchase Price Obligation	70,499	(6,188)	54,674	(31,116)
Income (loss) before income taxes and income (loss) from equity method investees	93,463	1,626	108,408	(20,700)
Income tax (expense) benefit	(176)	142	(417)	(141)
Income (loss) from equity method investees	350	270	(3,691)	(31,341)
Equity in (loss) earnings of consolidated subsidiaries	0	0	0	0
Net income (loss)	93,637	2,038	104,300	(52,182)
Consolidating adjustments
Revenues:
Gathering services and related fees	0	0	0	0
Natural gas, NGLs and condensate sales	0	0	0	0
Other revenues	0	0	0	0
Total revenues	0	0	0	0
Costs and expenses:
Cost of natural gas and NGLs	0	0	0	0
Operation and maintenance	0	0	0	0
General and administrative	0	0	0	0
Transaction costs			0	0
Depreciation and amortization	0	0	0	0
Loss on asset sales, net	0	0	0	0
Long-lived asset impairment	0	0	0	0
Total costs and expenses	0	0	0	0
Other income	0	0	0	0
Interest expense	0	0	0	0
Early extinguishment of debt			0
Deferred Purchase Price Obligation	0	0	0	0
Income (loss) before income taxes and income (loss) from equity method investees	0	0	0	0
Income tax (expense) benefit	0	0	0	0
Income (loss) from equity method investees	0	0	0	0
Equity in (loss) earnings of consolidated subsidiaries	(64,788)	(32,107)	(175,119)	(10,497)
Net income (loss)	(64,788)	(32,107)	(175,119)	(10,497)
Summit Midstream Partners, LP
Revenues:
Total revenues				266,412
Costs and expenses:
Net income (loss)				(54,927)
Summit Midstream Partners, LP | Reportable Legal Entities
Revenues:
Gathering services and related fees	0	0	0	0
Natural gas, NGLs and condensate sales	0	0	0	0
Other revenues	0	0	0	0
Total revenues	0	0	0	0
Costs and expenses:
Cost of natural gas and NGLs	0	0	0	0
Operation and maintenance	0	0	0	0
General and administrative	0	0	0	0
Transaction costs			119	1,296
Depreciation and amortization	352	154	660	424
Loss on asset sales, net	0	0	0	0
Long-lived asset impairment	0	0	0	0
Total costs and expenses	352	154	779	1,720
Other income	79	51	214	92
Interest expense	0	0	0	(1,441)
Early extinguishment of debt			0
Deferred Purchase Price Obligation	70,499	(6,188)	54,674	(31,116)
Income (loss) before income taxes and income (loss) from equity method investees	70,226	(6,291)	54,109	(34,185)
Income tax (expense) benefit	(176)	142	(417)	(141)
Income (loss) from equity method investees	0	0	0	0
Equity in (loss) earnings of consolidated subsidiaries	23,587	8,187	50,608	(17,856)
Net income (loss)	93,637	2,038	104,300	(52,182)
Co-Issuers | Reportable Legal Entities
Revenues:
Gathering services and related fees	0	0	0	0
Natural gas, NGLs and condensate sales	0	0	0	0
Other revenues	0	0	0	0
Total revenues	0	0	0	0
Costs and expenses:
Cost of natural gas and NGLs	0	0	0	0
Operation and maintenance	0	0	0	0
General and administrative	0	0	0	0
Transaction costs			0	0
Depreciation and amortization	0	0	0	0
Loss on asset sales, net	0	0	0	0
Long-lived asset impairment	0	0	0	0
Total costs and expenses	0	0	0	0
Other income	0	0	0	0
Interest expense	(17,614)	(15,733)	(51,883)	(46,209)
Early extinguishment of debt			(22,020)
Deferred Purchase Price Obligation	0	0	0	0
Income (loss) before income taxes and income (loss) from equity method investees	(17,614)	(15,733)	(73,903)	(46,209)
Income tax (expense) benefit	0	0	0	0
Income (loss) from equity method investees	0	0	0	0
Equity in (loss) earnings of consolidated subsidiaries	41,201	23,920	124,511	28,353
Net income (loss)	23,587	8,187	50,608	(17,856)
Guarantor Subsidiaries | Reportable Legal Entities
Revenues:
Gathering services and related fees	79,546	64,065	245,882	191,510
Natural gas, NGLs and condensate sales	22,828	9,578	44,355	25,747
Other revenues	5,202	4,612	17,043	13,286
Total revenues	107,576	78,255	307,280	230,543
Costs and expenses:
Cost of natural gas and NGLs	18,115	6,986	36,243	20,140
Operation and maintenance	19,044	20,800	60,812	64,413
General and administrative	11,555	10,183	34,317	31,072
Transaction costs			0	0
Depreciation and amortization	24,596	24,765	73,817	74,194
Loss on asset sales, net	(82)	13	(14)	24
Long-lived asset impairment	696	1,172	698	1,212
Total costs and expenses	73,924	63,919	205,873	191,055
Other income	0	0	0	0
Interest expense	0	0	0	0
Early extinguishment of debt			0
Deferred Purchase Price Obligation	0	0	0	0
Income (loss) before income taxes and income (loss) from equity method investees	33,652	14,336	101,407	39,488
Income tax (expense) benefit	0	0	0	0
Income (loss) from equity method investees	0	0	0	0
Equity in (loss) earnings of consolidated subsidiaries	0	0	0	0
Net income (loss)	33,652	14,336	101,407	39,488
Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenues:
Gathering services and related fees	16,524	16,231	53,002	43,073
Natural gas, NGLs and condensate sales	112	0	300	0
Other revenues	733	587	1,960	1,663
Total revenues	17,369	16,818	55,262	44,736
Costs and expenses:
Cost of natural gas and NGLs	62	0	85	0
Operation and maintenance	3,259	2,259	9,199	7,898
General and administrative	1,734	2,185	6,053	7,051
Transaction costs			0	0
Depreciation and amortization	3,979	3,060	11,707	9,052
Loss on asset sales, net	542	0	544	0
Long-lived asset impairment	594	0	879	529
Total costs and expenses	10,170	7,504	28,467	24,530
Other income	0	0	0	0
Interest expense	0	0	0	0
Early extinguishment of debt			0
Deferred Purchase Price Obligation	0	0	0	0
Income (loss) before income taxes and income (loss) from equity method investees	7,199	9,314	26,795	20,206
Income tax (expense) benefit	0	0	0	0
Income (loss) from equity method investees	350	270	(3,691)	(31,341)
Equity in (loss) earnings of consolidated subsidiaries	0	0	0	0
Net income (loss)	$ 7,549	$ 9,584	$ 23,104	$ (11,135)

CONDENSED CONSOLIDATING FINAN81

CONDENSED CONSOLIDATING FINANCIAL INFORMATION - Condensed Cash Flow Statement (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net cash provided by (used in) operating activities	$ 196,497	$ 168,705
Cash flows from investing activities:
Capital expenditures	(86,206)	(122,735)
Proceeds from asset sale	2,300	0
Contributions to equity method investees	(21,581)	(20,157)
Acquisitions of gathering systems from affiliate	0	(359,431)
Other, net	(579)	(373)
Advances to affiliates	0	0
Net cash provided by (used in) investing activities	(106,066)	(502,696)
Cash flows from financing activities:
Distributions to unitholders	(134,066)	(123,064)
Borrowings under Revolving Credit Facility	177,500	490,300
Repayments under Revolving Credit Facility	(319,500)	(189,300)
Debt issuance costs	(15,891)	(3,013)
Payment of redemption and call premiums on senior notes	(17,913)	0
Proceeds from ATM Program issuances, net of costs	17,251	0
Proceeds from issuance of common units, net	0	126,115
Contribution from General Partner	465	2,702
Issuance of senior notes	500,000	0
Tender and redemption of senior notes	(300,000)	0
Cash advance from Summit Investments to contributed subsidiaries, net	0	12,214
Expenses paid by Summit Investments on behalf of contributed subsidiaries	0	4,821
Other, net	(2,794)	(980)
Advances from affiliates	0	0
Net cash provided by (used in) financing activities	(94,948)	319,795
Net change in cash and cash equivalents	(4,517)	(14,196)
Cash and cash equivalents, beginning of period	7,428	21,793
Cash and cash equivalents, end of period	2,911	7,597
Consolidating adjustments
Cash flows from operating activities:
Net cash provided by (used in) operating activities	0	0
Cash flows from investing activities:
Capital expenditures	0	0
Proceeds from asset sale	0
Contributions to equity method investees	0	0
Acquisitions of gathering systems from affiliate		0
Other, net	0	0
Advances to affiliates	85,013	386,758
Net cash provided by (used in) investing activities	85,013	386,758
Cash flows from financing activities:
Distributions to unitholders	0	0
Borrowings under Revolving Credit Facility	0	0
Repayments under Revolving Credit Facility	0	0
Debt issuance costs	0	0
Payment of redemption and call premiums on senior notes	0
Proceeds from ATM Program issuances, net of costs	0
Proceeds from issuance of common units, net		0
Contribution from General Partner	0	0
Issuance of senior notes	0
Tender and redemption of senior notes	0
Cash advance from Summit Investments to contributed subsidiaries, net		0
Expenses paid by Summit Investments on behalf of contributed subsidiaries		0
Other, net	0	0
Advances from affiliates	(85,013)	(386,758)
Net cash provided by (used in) financing activities	(85,013)	(386,758)
Net change in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	0	0
Summit Midstream Partners, LP | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by (used in) operating activities	5,707	3,740
Cash flows from investing activities:
Capital expenditures	(995)	(904)
Proceeds from asset sale	0
Contributions to equity method investees	0	0
Acquisitions of gathering systems from affiliate		(359,431)
Other, net	(579)	(373)
Advances to affiliates	14,896	(16,822)
Net cash provided by (used in) investing activities	13,322	(377,530)
Cash flows from financing activities:
Distributions to unitholders	(134,066)	(123,064)
Borrowings under Revolving Credit Facility	0	12,000
Repayments under Revolving Credit Facility	0	0
Debt issuance costs	0	0
Payment of redemption and call premiums on senior notes	0
Proceeds from ATM Program issuances, net of costs	17,251
Proceeds from issuance of common units, net		126,115
Contribution from General Partner	465	2,702
Issuance of senior notes	0
Tender and redemption of senior notes	0
Cash advance from Summit Investments to contributed subsidiaries, net		(12,000)
Expenses paid by Summit Investments on behalf of contributed subsidiaries		3,030
Other, net	(2,794)	(980)
Advances from affiliates	99,909	369,936
Net cash provided by (used in) financing activities	(19,235)	377,739
Net change in cash and cash equivalents	(206)	3,949
Cash and cash equivalents, beginning of period	698	73
Cash and cash equivalents, end of period	492	4,022
Co-Issuers | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by (used in) operating activities	(45,854)	(52,916)
Cash flows from investing activities:
Capital expenditures	0	0
Proceeds from asset sale	0
Contributions to equity method investees	0	0
Acquisitions of gathering systems from affiliate		0
Other, net	0	0
Advances to affiliates	21,658	(245,093)
Net cash provided by (used in) investing activities	21,658	(245,093)
Cash flows from financing activities:
Distributions to unitholders	0	0
Borrowings under Revolving Credit Facility	177,500	478,300
Repayments under Revolving Credit Facility	(319,500)	(189,300)
Debt issuance costs	(15,891)	(3,013)
Payment of redemption and call premiums on senior notes	(17,913)
Proceeds from ATM Program issuances, net of costs	0
Proceeds from issuance of common units, net		0
Contribution from General Partner	0	0
Issuance of senior notes	500,000
Tender and redemption of senior notes	(300,000)
Cash advance from Summit Investments to contributed subsidiaries, net		0
Expenses paid by Summit Investments on behalf of contributed subsidiaries		0
Other, net	0	0
Advances from affiliates	0	0
Net cash provided by (used in) financing activities	24,196	285,987
Net change in cash and cash equivalents	0	(12,022)
Cash and cash equivalents, beginning of period	51	12,407
Cash and cash equivalents, end of period	51	385
Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by (used in) operating activities	174,335	159,650
Cash flows from investing activities:
Capital expenditures	(60,279)	(39,630)
Proceeds from asset sale	0
Contributions to equity method investees	0	0
Acquisitions of gathering systems from affiliate		0
Other, net	0	0
Advances to affiliates	(118,175)	(124,843)
Net cash provided by (used in) investing activities	(178,454)	(164,473)
Cash flows from financing activities:
Distributions to unitholders	0	0
Borrowings under Revolving Credit Facility	0	0
Repayments under Revolving Credit Facility	0	0
Debt issuance costs	0	0
Payment of redemption and call premiums on senior notes	0
Proceeds from ATM Program issuances, net of costs	0
Proceeds from issuance of common units, net		0
Contribution from General Partner	0	0
Issuance of senior notes	0
Tender and redemption of senior notes	0
Cash advance from Summit Investments to contributed subsidiaries, net		0
Expenses paid by Summit Investments on behalf of contributed subsidiaries		0
Other, net	0	0
Advances from affiliates	0	0
Net cash provided by (used in) financing activities	0	0
Net change in cash and cash equivalents	(4,119)	(4,823)
Cash and cash equivalents, beginning of period	5,647	6,930
Cash and cash equivalents, end of period	1,528	2,107
Non-Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by (used in) operating activities	62,309	58,231
Cash flows from investing activities:
Capital expenditures	(24,932)	(82,201)
Proceeds from asset sale	2,300
Contributions to equity method investees	(21,581)	(20,157)
Acquisitions of gathering systems from affiliate		0
Other, net	0	0
Advances to affiliates	(3,392)	0
Net cash provided by (used in) investing activities	(47,605)	(102,358)
Cash flows from financing activities:
Distributions to unitholders	0	0
Borrowings under Revolving Credit Facility	0	0
Repayments under Revolving Credit Facility	0	0
Debt issuance costs	0	0
Payment of redemption and call premiums on senior notes	0
Proceeds from ATM Program issuances, net of costs	0
Proceeds from issuance of common units, net		0
Contribution from General Partner	0	0
Issuance of senior notes	0
Tender and redemption of senior notes	0
Cash advance from Summit Investments to contributed subsidiaries, net		24,214
Expenses paid by Summit Investments on behalf of contributed subsidiaries		1,791
Other, net	0	0
Advances from affiliates	(14,896)	16,822
Net cash provided by (used in) financing activities	(14,896)	42,827
Net change in cash and cash equivalents	(192)	(1,300)
Cash and cash equivalents, beginning of period	1,032	2,383
Cash and cash equivalents, end of period	$ 840	$ 1,083