Summit Midstream Partners (SMLP) 10-Q 8 May 20 2020 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Cover [Abstract]
Entity Registrant Name	Summit Midstream Partners, LP
Entity Central Index Key	0001549922
Document Type	10-Q
Document Period End Date	Mar. 31, 2020
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		94,558,166
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Title of 12(b) Security	Common Units
Trading Symbol	SMLP
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-35666
Entity Tax Identification Number	45-5200503
Entity Address, Address Line One	910 Louisiana Street
Entity Address, Address Line Two	Suite 4200
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77002
City Area Code	832
Local Phone Number	413-4770
Document Quarterly Report	true
Entity Interactive Data Current	Yes
Document Transition Report	false
Entity Incorporation, State or Country Code	DE

UNAUDITED CONDENSED CONSOLIDATE

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 67,694	$ 4,948
Restricted cash	4,057	27,392
Accounts receivable	83,648	102,118
Other current assets	4,265	5,018
Total current assets	159,664	139,476
Property, plant and equipment, net	1,869,882	1,882,251
Intangible assets, net	224,076	232,278
Investment in equity method investees	363,578	309,728
Other noncurrent assets	7,735	9,718
Total assets	2,624,935	2,573,451
Current liabilities:
Trade accounts payable	22,294	24,415
Accrued expenses	11,413	11,482
Due to affiliate	776	311
Deferred revenue	14,318	13,493
Ad valorem taxes payable	3,696	8,477
Accrued interest	15,370	12,311
Accrued environmental remediation	2,016	1,725
Other current liabilities	8,621	11,933
Total current liabilities	78,504	84,147
Long-term debt	1,491,716	1,470,299
Deferred Purchase Price Obligation	180,750	178,453
Noncurrent deferred revenue	43,045	38,709
Noncurrent accrued environmental remediation	2,618	2,926
Other noncurrent liabilities	8,044	7,951
Total liabilities	1,804,677	1,782,485
Commitments and contingencies (Note 15)
Partners' Capital
Series A Preferred Units (300,000 units issued and outstanding at March 31, 2020 and December 31, 2019)	300,741	293,616
Common limited partner capital (94,469,385 units issued and outstanding at March 31, 2020 and 93,493,473 units issued and outstanding at December 31, 2019)	457,176	469,900
Total partners' capital	757,917	763,516
Total liabilities, mezzanine capital and partners' capital	2,624,935	2,573,451
Mezzanine Capital
Mezzanine Capital
Subsidiary Series A Preferred Units (66,002 units issued and outstanding at March 31, 2020 and 30,058 units issued and outstanding at December 31, 2019)	$ 62,341	$ 27,450

UNAUDITED CONDENSED CONSOLIDA_2

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares	Mar. 31, 2020	Dec. 31, 2019
Subsidiary Series A preferred unitholders, issued	300,000	300,000
Subsidiary Series A preferred unitholders, outstanding	300,000	300,000
Common limited partner capital (in shares), issued	94,469,385	93,493,473
Common limited partner capital (in shares), outstanding	94,469,385	93,493,473
Mezzanine Capital
Subsidiary Series A preferred unitholders, issued	66,002	30,058
Subsidiary Series A preferred unitholders, outstanding	66,002	30,058

UNAUDITED CONDENSED CONSOLIDA_3

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues:
Total revenues	$ 104,903	$ 131,408
Costs and expenses:
Cost of natural gas and NGLs	$ 8,225	$ 31,759
Type of Cost, Good or Service [Extensible List]	us-gaap:OilAndGasPurchasedMember	us-gaap:OilAndGasPurchasedMember
Operation and maintenance	$ 21,811	$ 24,222
General and administrative	16,378	17,281
Depreciation and amortization	29,629	27,727
Transaction costs	11	950
Loss (gain) on asset sales, net	115	(961)
Long-lived asset impairment	3,821	44,951
Total costs and expenses	79,990	145,929
Other (expense) income	(428)	209
Interest expense	(20,218)	(17,527)
Deferred Purchase Price Obligation	(2,297)	(4,427)
Income (loss) before income taxes and income (loss) from equity method investees	1,970	(36,266)
Income tax benefit (expense)	28	(207)
Income (loss) from equity method investees	3,311	(441)
Net income (loss)	5,309	(36,914)
Net income attributable to General Partner, including IDRs	0	12
Net income (loss) attributable to limited partners	5,309	(36,926)
Series A Preferred Units
Costs and expenses:
Net income (loss) attributable to limited partners	7,125	7,125
Series A Preferred Units | Subsidiary
Costs and expenses:
Net income (loss) attributable to limited partners	945	0
Common units
Costs and expenses:
Net income (loss) attributable to limited partners	$ (2,761)	$ (44,051)
Loss per limited partner unit:
Basic (in dollars per share)	$ (0.03)	$ (0.58)
Diluted (in dollars per share)	$ (0.03)	$ (0.58)
Weighted-average limited partner units outstanding:
Basic (shares)	93,675	75,793
Diluted (shares)	93,675	75,793
Gathering Services and Related Fees
Revenues:
Total revenues	$ 83,792	$ 86,964
Natural Gas, NGLs and Condensate Sales
Revenues:
Total revenues	13,780	37,928
Other Revenues
Revenues:
Total revenues	$ 7,331	$ 6,516

UNAUDITED CONDENSED CONSOLIDA_4

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF PARTNERS' CAPITAL - USD ($) $ in Thousands	Total	Limited partners, Series A Preferred Units	Common	General Partner
Beginning balance at Dec. 31, 2018	$ 1,221,224	$ 293,616	$ 902,358	$ 25,250
Net income (loss)	(36,914)	7,125	(44,051)	12
Conversion of General Partner economic interests	0	0	22,222	(22,222)
Distributions to unitholders	(45,281)	0	(42,241)	(3,040)
Unit-based compensation	2,526	0	2,526	0
Tax withholdings and associated payments on vested SMLP LTIP awards	(2,522)	0	(2,522)	0
Ending balance at Mar. 31, 2019	1,139,033	300,741	838,292	$ 0
Beginning balance at Dec. 31, 2019	763,516	293,616	469,900
Net income (loss)	4,364	7,125	(2,761)
Distributions to unitholders	(11,702)	0	(11,702)
Unit-based compensation	2,723	0	2,723
Tax withholdings and associated payments on vested SMLP LTIP awards	(984)	0	(984)
Ending balance at Mar. 31, 2020	$ 757,917	$ 300,741	$ 457,176

UNAUDITED CONDENSED CONSOLIDA_5

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income (loss)	$ 5,309	$ (36,914)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	29,863	28,116
Noncash lease expense	473	765
Amortization of debt issuance costs	1,109	1,080
Deferred Purchase Price Obligation	2,297	4,427
Unit-based and noncash compensation	2,723	2,526
(Income) loss from equity method investees	(3,311)	441
Distributions from equity method investees	7,494	8,583
Loss (gain) on asset sales, net	115	(961)
Long-lived asset impairment	3,821	44,951
Changes in operating assets and liabilities:
Accounts receivable	18,470	4,675
Trade accounts payable	3,960	271
Accrued expenses	(69)	(1,199)
Due from affiliate	465	80
Deferred revenue, net	5,161	2,323
Ad valorem taxes payable	(4,781)	(6,184)
Accrued interest	3,059	3,111
Accrued environmental remediation, net	(17)	(548)
Other, net	(2,173)	(2,832)
Net cash provided by operating activities	73,968	52,711
Cash flows from investing activities:
Capital expenditures	(18,583)	(60,848)
Proceeds from asset sale (net of cash of $1,475 for the period ended March 31, 2019)	0	89,461
Investment in equity method investee	(58,033)	0
Other, net	217	(120)
Net cash (used in) provided by investing activities	(76,399)	28,493
Cash flows from financing activities:
Distributions to unitholders	(11,702)	(45,281)
Borrowings under Revolving Credit Facility	55,000	69,000
Repayments under Revolving Credit Facility	(34,000)	(101,000)
Proceeds from issuance of Series A preferred units, net of costs	33,946	0
Other, net	(1,402)	(2,968)
Net cash provided by (used in) financing activities	41,842	(80,249)
Net change in cash, cash equivalents and restricted cash	39,411	955
Cash, cash equivalents and restricted cash, beginning of period	32,340	4,345
Cash, cash equivalents and restricted cash, end of period	71,751	5,300
Supplemental cash flow disclosures:
Cash interest paid	16,523	15,229
Less capitalized interest	491	1,915
Interest paid (net of capitalized interest)	16,032	13,314
Cash paid for taxes	0	0
Noncash investing and financing activities
Capital expenditures in trade accounts payable (period-end accruals)	13,765	23,389
ASC Topic 842
Noncash investing and financing activities
Right-of-use assets relating to ASC Topic 842	$ 0	$ 5,448

UNAUDITED CONDENSED CONSOLIDA_6

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Statement Of Cash Flows [Abstract]
Net of cash	$ 1,475
Cash and cash equivalents	5,300
Restricted cash	0
Total cash, cash equivalents and restricted cash	$ 5,300

ORGANIZATION, BUSINESS OPERATIO

ORGANIZATION, BUSINESS OPERATIONS AND PRESENTATION AND CONSOLIDATION	3 Months Ended
	Mar. 31, 2020
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. SMLP is a value-oriented limited partnership focused on developing, owning and operating midstream energy infrastructure assets that are strategically located in 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 March 31, 2020, SMP Holdings, a wholly owned subsidiary of Summit Investments, beneficially owned 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, compression, treating and processing services as well as crude oil and produced water gathering services pursuant to primarily long-term, fee-based agreements with our customers. Our results are primarily driven by the volumes of natural gas that we gather, compress, treat and/or 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 and transportation systems: • Summit Utica, a natural gas gathering system operating in the Appalachian Basin, which includes the Utica and Point Pleasant shale formations in southeastern Ohio; • 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; • Polar and Divide, a crude oil and produced water gathering system and transmission pipeline operating in the Williston Basin, which includes the Bakken and Three Forks shale formations in northwestern North Dakota; • 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; • 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 and southeastern Wyoming; • Summit Permian, an associated natural gas gathering and processing system operating in the northern Delaware Basin, which includes the Wolfcamp and Bone Spring formations, in southeastern New Mexico; • Double E, a 1.35 Bcf/d natural gas transmission pipeline that is under development and will provide transportation service from multiple receipt points in the Delaware Basin to various delivery points in and around the Waha Hub in Texas; • Grand River, a natural gas gathering and processing system operating in the Piceance Basin, which includes the Mesaverde formation and the Mancos and Niobrara shale formations in western Colorado; • DFW Midstream, a natural gas gathering system operating in the Fort Worth Basin, which includes the Barnett Shale formation in north-central Texas; and • Mountaineer Midstream, a natural gas gathering system operating in the Appalachian Basin, which includes the Marcellus Shale formation in northern West Virginia. O ther than our investment s in Double E and Ohio Gathering, all of our business activities are conducted through wholly owned operating subsidiaries. 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 revenues and expenses and the disclosure of commitments and contingencies. Further, these estimates and other factors, including those outside of our control, such as the impact of lower commodity prices, may have a significant negative impact to our business, financial condition, results of operations and cash flows. Although management believes these estimates are reasonable, actual results could differ from its estimates. 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 the 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 which are necessary to fairly present the unaudited condensed consolidated balance sheet as of March 31, 2020, the unaudited condensed consolidated statements of operations and statements of partners’ capital for the three months ended March 31, 2020 and 2019 and the unaudited condensed consolidated statements of cash flows for the three months ended March 31, 2020 and 2019. The balance sheet at December 31, 2019 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, 2019, as filed with the SEC on March 9, 2020 (the "2019 Annual Report"). The results of operations for an interim period are not necessarily indicative of results expected for a full year. Risks and Uncertainties. We are closely monitoring the impact of the outbreak of COVID-19 on all aspects of our business, including how it will impact our customers, employees, supply chain and distribution network. While COVID-19 did not have a material adverse effect on our reported results for the first quarter of 2020, only one month of the quarter was affected by COVID-19 and if the current conditions continue, subsequent quarters may reflect these conditions for a full quarter. We are unable to predict the ultimate impact that COVID-19 may have on our business, future results of operations, financial position or cash flows. The full extent to which our operations may be impacted by the COVID-19 pandemic will depend largely on future developments, which are highly uncertain and cannot be accurately predicted, including new information which may emerge concerning the severity of the outbreak and actions by government authorities to contain the outbreak or treat its impact. Furthermore, the impacts of a potential worsening of global economic conditions and the continued disruptions to and volatility in the financial markets remain unknown.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Except for the changes below, there have been no changes to our significant accounting policies since December 31, 2019. 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 . We have recently adopted the following accounting pronouncement: • ASU No. 2018-13 Fair Value Measurement (“ASU 2018-13”). ASU 2018-13 updates the disclosure requirements on fair value measurements including new disclosures for the changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. ASU 2018-13 modifies existing disclosures including clarifying the measurement uncertainty disclosure. ASU 2018-13 removes certain existing disclosure requirements including the amount and reasons for transfers between Level 1 and Level 2 fair value measurements and the policy for the timing of transfer between levels. The adoption of ASU 2018-13 on January 1, 2020 did not have a material impact on our unaudited condensed consolidated financial statement disclosures. • ASU No. 2016-13 Financial Instruments – Credit Losses (“ASU 2016-13”). ASU 2016-13 requires the use of a current expected loss model for financial assets measured at amortized cost and certain off-balance sheet credit exposures. Under this model, entities will be required to estimate the lifetime expected credit losses on such instruments based on historical experience, current conditions, and reasonable and supportable forecasts. This amended guidance also expands the disclosure requirements to enable users of financial statements to understand an entity’s assumptions, models and methods for estimating expected credit losses. The changes are effective for annual and interim periods beginning after December 15, 2019, and amendments should be applied using a modified retrospective approach. The adoption of ASU 2016-13 on January 1, 2020 did not have a material impact on our unaudited condensed consolidated financial statements or disclosures. Accounting Pronouncements Pending Adoption • ASU No. 2020-04 Reference Rate Reform (“ASU 2020-04”). ASU 2020-04 provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions affected by reference rate reform on financial reporting. The amendments in ASU 2020-04 are effective as of March 12, 2020 through December 31, 2022. We are currently evaluating the provisions of ASU 2020-04 to determine its impact on our unaudited condensed consolidated financial statements and disclosures.

REVENUE

REVENUE	3 Months Ended
	Mar. 31, 2020
Revenue From Contract With Customer [Abstract]
REVENUE	3. REVENUE The majority of our revenue is derived from long-term, fee-based contracts with our customers, which include original terms of up to 25 years. We recognize revenue earned from fee-based gathering, compression, treating and processing services in Gathering services and related fees. We also earn revenue in the Williston Basin and Permian Basin reporting segments from the sale of physical natural gas purchased from our customers under certain percent-of-proceeds arrangements. Under ASC Topic 606, these gathering contracts are presented net within Cost of natural gas and NGLs. We sell natural gas that we retain from certain customers in the Barnett Shale reporting segment to offset the power expenses of the electric-driven compression on the DFW Midstream system. We also sell condensate and NGLs retained from certain of our gathering services in the Piceance Basin and Permian Basin reporting segments. Revenues from the sale of natural gas and condensate are recognized in Natural gas, NGLs and condensate sales; the associated expense is included in Operation and maintenance expense. Certain customers reimburse us for costs we incur on their behalf. We record costs incurred and reimbursed by our customers on a gross basis, with the revenue component recognized in Other revenues. The transaction price in our contracts is primarily based on the volume of natural gas, crude oil or produced water transferred by our gathering systems to the customer’s agreed upon delivery point multiplied by the contractual rate. For contracts that include MVCs, variable consideration up to the MVC will be included in the transaction price. For contracts that do not include MVCs, we do not estimate variable consideration because the performance obligations are completed and settled on a daily basis. For contracts containing noncash consideration such as fuel received in-kind, we measure the transaction price at the point of sale when the volume, mix and market price of the commodities are known . We have contracts with MVCs that are variable and constrained. Contracts with greater than monthly MVCs are reviewed on a quarterly basis and adjustments to those estimates are made during each respective reporting period, if necessary. The transaction price is allocated if the contract contains more than one performance obligation such as contracts that include MVCs. The transaction price allocated is based on the MVC for the applicable measurement period. Performance obligations. The majority of our contracts have a single performance obligation which is either to provide gathering services (an integrated service) or sell natural gas, NGLs and condensate, which are both satisfied when the related natural gas, crude oil and produced water are received and transferred to an agreed upon delivery point. We also have certain contracts with multiple performance obligations. They include an option for the customer to acquire additional services such as contracts containing MVCs. These performance obligations would also be satisfied when the related natural gas, crude oil and produced water are received and transferred to an agreed upon delivery point. In these instances, we allocate the contract’s transaction price to each performance obligation using our best estimate of the standalone selling price of each service in the contract. Performance obligations for gathering services are generally satisfied over time. We utilize either an output method (i.e., measure of progress) for guaranteed, stand-ready service contracts or an asset/system delivery time estimate for non-guaranteed, as-available service contracts. Performance obligations for the sale of natural gas, NGLs and condensate are satisfied at a point in time. There are no significant judgments for these transactions because the customer obtains control based on an agreed upon delivery point. Certain of our gathering and/or processing agreements provide for monthly or annual MVCs. Under these MVCs, our customers agree to ship and/or process a minimum volume of production on our gathering systems or to pay a minimum monetary amount over certain periods during the term of the MVC. A customer must make a shortfall payment to us at the end of the contracted measurement period if its actual throughput volumes are less than its contractual MVC for that period. Certain customers are entitled to utilize shortfall payments to offset gathering fees in one or more subsequent contracted measurement periods to the extent that such customer's throughput volumes in a subsequent contracted measurement period exceed its MVC for that contracted measurement period. We recognize customer obligations under their MVCs as revenue and contract assets when (i) we consider it remote that the customer will utilize shortfall payments to offset gathering or processing fees in excess of its MVCs in subsequent periods; (ii) the customer incurs a shortfall in a contract with no banking mechanism or claw back provision; (iii) the customer’s banking mechanism has expired; or (iv) it is remote that the customer will use its unexercised right. Our services are typically billed on a monthly basis and we do not offer extended payment terms. We do not have contracts with financing components. The following table presents estimated revenue expected to be recognized during the remainder of 2020 and over the remaining contract period related to performance obligations that are unsatisfied and are comprised of estimated MVC shortfall payments. We applied the practical expedient in paragraph 606-10-50-14 of ASC Topic 606 for certain arrangements that we consider optional purchases (i.e., there is no enforceable obligation for the customer to make purchases) and those amounts are therefore excluded from the table. 2020 2021 2022 2023 2024 Thereafter (In thousands) Gathering services and related fees $ 86,916 $ 102,127 $ 84,736 $ 66,693 $ 50,608 $ 58,672 Revenue by Category. In the following table, revenue is disaggregated by geographic area and major products and services. Ohio Gathering is excluded from the tables below due to equity method accounting. For more detailed information about reportable segments, see Note 4. Reportable Segments Three months ended March 31, 2020 Utica Shale Williston Basin DJ Basin Permian Basin Piceance Basin Barnett Shale Marcellus Shale Total reportable segments All other segments Total (In thousands) Major products / services lines Gathering services and related fees $ 6,962 $ 23,797 $ 6,855 $ 2,311 $ 27,189 $ 10,443 $ 6,235 $ 83,792 $ — $ 83,792 Natural gas, NGLs and condensate sales — 4,324 70 4,512 1,003 3,871 — 13,780 — 13,780 Other revenues — 3,142 1,034 187 1,065 1,260 — 6,688 643 7,331 Total $ 6,962 $ 31,263 $ 7,959 $ 7,010 $ 29,257 $ 15,574 $ 6,235 $ 104,260 $ 643 $ 104,903 Reportable Segments Three months ended March 31, 2019 Utica Shale Williston Basin DJ Basin Permian Basin Piceance Basin Barnett Shale Marcellus Shale Total reportable segments All other segments Total (In thousands) Major products / services lines Gathering services and related fees $ 7,495 $ 25,706 $ 3,724 $ 366 $ 31,840 $ 13,025 $ 6,197 $ 88,353 $ (1,389 ) $ 86,964 Natural gas, NGLs and condensate sales — 5,585 85 4,221 2,302 604 — 12,797 25,131 37,928 Other revenues — 2,908 1,007 32 1,138 1,656 — 6,741 (225 ) 6,516 Total $ 7,495 $ 34,199 $ 4,816 $ 4,619 $ 35,280 $ 15,285 $ 6,197 $ 107,891 $ 23,517 $ 131,408 Contract balances. Contract assets relate to our rights to consideration for work completed but not billed at the reporting date and consist of the estimated MVC shortfall payments expected from our customers and unbilled activity associated with contributions in aid of construction. Contract assets are transferred to trade receivables when the rights become unconditional. The following table provides information about contract assets from contracts with customers: March 31, 2020 December 31, 2019 (In thousands) Contract assets, beginning of period $ 3,902 $ 8,755 Additions 13,877 18,077 Transfers out (425 ) (22,930 ) Contract assets, end of period $ 17,354 $ 3,902 As of March 31, 2020, receivables with customers totaled $58.0 million and contract assets totaled $17.4 million which were included in the Accounts receivable caption on the unaudited condensed consolidated balance sheet. As of December 31, 2019, receivables with customers totaled $90.4 million and contract assets totaled $3.9 million which were included in the Accounts receivable caption on the unaudited condensed consolidated balance sheet. Contract liabilities (deferred revenue) relate to the advance consideration received from customers primarily for contributions in aid of construction. We recognize contract liabilities under these arrangements in revenue over the contract period. For the three months ended March 31, 2020 and 2019, we recognized $2.4 million and $2.7 million of gathering services and related fees which were included in the contract liability balance as of the beginning of the period. See Note 8 for additional details.

SEGMENT INFORMATION

SEGMENT INFORMATION	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
SEGMENT INFORMATION	4. SEGMENT INFORMATION As of March 31, 2020, 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 Polar and Divide and Bison Midstream; • the DJ Basin, which is served by Niobrara G&P; • the Permian Basin, which is served by Summit Permian; • the Piceance Basin, which is served by Grand River; • the Barnett Shale, which is served by DFW Midstream; and • the Marcellus Shale, which is served by Mountaineer Midstream. Until March 22, 2019, we owned Tioga Midstream, a crude oil, produced water and associated natural gas gathering system operating in the Williston Basin. Until December 1, 2019, we owned certain assets in the Red Rock Gathering system operating in the Piceance Basin. Refer to Note 16 to the unaudited condensed consolidated financial statements for details on the sale of Tioga 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. The Ohio Gathering reportable segment includes our investment in Ohio Gathering. Income or loss from equity method investees, as reflected on the unaudited condensed consolidated statements of operations, relates to Ohio Gathering and is recognized and disclosed on a one-month lag (see Note 7). For the three months ended March 31, 2020, other than the investment activity described in Note 7, Double E did not have any results of operations given that the Double E Project is currently under development. The Double E Project is expected to be operational in the third quarter of 2021. Corporate and Other represents those results that are: (i) not specifically attributable to a reportable segment; (ii) not individually reportable (such as Double E); 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, certain natural gas and crude oil marketing services, construction management fees related to the Double E Project and transaction costs. Assets by reportable segment follow. March 31, 2020 December 31, 2019 (In thousands) Assets (1): Utica Shale $ 205,341 $ 206,368 Ohio Gathering 271,268 275,000 Williston Basin 452,684 452,152 DJ Basin 200,473 205,308 Permian Basin 184,043 185,708 Piceance Basin 622,403 631,140 Barnett Shale 345,248 350,638 Marcellus Shale 184,279 184,631 Total reportable segment assets 2,465,739 2,490,945 Corporate and Other 159,196 82,506 Total assets $ 2,624,935 $ 2,573,451 (1) At March 31, 2020, Corporate and Other included $92.3 million relating to our investment in Double E (included in the Investment in equity method investees caption of the unaudited condensed consolidated balance sheet). At December 31, 2019, Corporate and Other included $34.7 million relating to our investment in Double E. Revenues by reportable segment follow. Three months ended March 31, 2020 2019 (In thousands) Revenues (1): Utica Shale $ 6,962 $ 7,495 Williston Basin 31,263 34,199 DJ Basin 7,959 4,816 Permian Basin 7,010 4,619 Piceance Basin 29,257 35,280 Barnett Shale 15,574 15,285 Marcellus Shale 6,235 6,197 Total reportable segments revenue 104,260 107,891 Corporate and Other 643 26,838 Eliminations — (3,321 ) Total revenues $ 104,903 $ 131,408 (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 March 31, 2020 2019 Percentage of total revenues (1): Counterparty A - Piceance Basin 11 % * (1) 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 gas gathering contracts as reported in Other revenues, by reportable segment follows. Three months ended March 31, 2020 2019 (In thousands) Depreciation and amortization (1): Utica Shale $ 1,927 $ 1,908 Williston Basin 6,495 5,436 DJ Basin 1,527 799 Permian Basin 1,345 1,072 Piceance Basin 11,298 11,791 Barnett Shale (2) 4,032 4,330 Marcellus Shale 2,300 2,283 Total reportable segment depreciation and amortization 28,924 27,619 Corporate and Other 939 497 Total depreciation and amortization $ 29,863 $ 28,116 (1) Excludes depreciation and amortization recognized by Ohio Gathering due to equity method accounting. (2) Includes the amortization expense associated with our favorable gas gathering contracts as reported in Other revenues . Cash paid for capital expenditures by reportable segment follow. Three months ended March 31, 2020 2019 (In thousands) Cash paid for capital expenditures (1): Utica Shale $ 909 $ 101 Williston Basin 4,943 8,023 DJ Basin 6,298 28,356 Permian Basin 3,281 7,057 Piceance Basin 346 1,226 Barnett Shale (2) 657 (118 ) Marcellus Shale 422 102 Total reportable segment capital expenditures 16,856 44,747 Corporate and Other 1,727 16,101 Total cash paid for capital expenditures $ 18,583 $ 60,848 (1) Excludes cash paid for capital expenditures by Ohio Gathering due to equity method accounting. (2) For the three months ended March 31, 2019, the amount includes sales tax reimbursements of $1.1 million. During the three months ended March 31, 2019, Corporate and Other included cash paid of $0.3 million for corporate purposes; the remainder represents capital expenditures relating to the Double E Project. We assess the performance of our reportable segments based on segment adjusted EBITDA. We define segment adjusted EBITDA as total revenues less total costs and expenses; plus (i) other income excluding interest income, (ii) our proportional adjusted EBITDA for equity method investees, (iii) depreciation and amortization, (iv) adjustments related to MVC shortfall payments, (v) adjustments related to capital reimbursement activity, (vi) unit-based and noncash compensation, (vii) change in the Deferred Purchase Price Obligation fair value, (viii) impairments, (ix) other noncash expenses or losses, less other noncash income or gains and (x) restructuring expenses. We define proportional adjusted EBITDA for our equity method investees as the product of (i) total revenues less total expenses, excluding impairments and other noncash income or expense items, and amortization for deferred contract costs; and (ii) our ownership interest in Ohio Gathering during the respective period. 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), certain natural gas and crude oil marketing services, transaction costs, interest expense, change in the Deferred Purchase Price Obligation fair value and income tax expense or benefit from segment adjusted EBITDA. Segment adjusted EBITDA by reportable segment follows. Three months ended March 31, 2020 2019 (In thousands) Reportable segment adjusted EBITDA Utica Shale $ 5,928 $ 6,193 Ohio Gathering 7,939 9,210 Williston Basin 16,192 18,734 DJ Basin 5,911 2,673 Permian Basin 1,581 (550 ) Piceance Basin 23,557 25,999 Barnett Shale 8,760 11,374 Marcellus Shale 5,320 5,142 Total of reportable segments' measures of profit $ 75,188 $ 78,775 A 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 follows. Three months ended March 31, 2020 2019 (In thousands) Reconciliation of income (loss) before income taxes and income (loss) from equity method investees to total of reportable segments' measures of profit: Income (loss) before income taxes and income (loss) from equity method investees $ 1,970 $ (36,266 ) Add: Corporate and Other expense 11,895 14,159 Interest expense 20,218 17,527 Deferred Purchase Price Obligation 2,297 4,427 Depreciation and amortization 29,863 28,116 Proportional adjusted EBITDA for equity method investees 7,939 9,210 Adjustments related to MVC shortfall payments (5,442 ) (4,199 ) Adjustments related to capital reimbursement activity (211 ) (715 ) Unit-based and noncash compensation 2,723 2,526 Loss (gain) on asset sales, net 115 (961 ) Long-lived asset impairment 3,821 44,951 Total of reportable segments' measures of profit $ 75,188 $ 78,775 Adjustments related to MVC shortfall payments recognize the earnings from MVC shortfall payments ratably over the term of the associated MVC (see Note 3). Contributions in aid of construction are recognized over the remaining term of the respective contract. We include adjustments related to capital reimbursement activity in our calculation of segment adjusted EBITDA to account for revenue recognized from contributions in aid of construction. Adjustments related to MVC shortfall payments by reportable segment follow. Three months ended March 31, 2020 Williston Basin Piceance Basin Barnett Shale Total (In thousands) Adjustments related to expected MVC shortfall payments: $ (5,665 ) $ 223 $ — $ (5,442 ) Three months ended March 31, 2019 Williston Basin Piceance Basin Barnett Shale Total (In thousands) Adjustments related to expected MVC shortfall payments: $ (5,549 ) $ (103 ) $ 1,453 $ (4,199 )

PROPERTY, PLANT, AND EQUIPMENT,

PROPERTY, PLANT, AND EQUIPMENT, NET	3 Months Ended
	Mar. 31, 2020
Property Plant And Equipment [Abstract]
PROPERTY, PLANT, AND EQUIPMENT, NET	5. PROPERTY, PLANT AND EQUIPMENT, NET Details on property, plant and equipment follow. March 31, 2020 December 31, 2019 (In thousands) Gathering and processing systems and related equipment $ 2,193,225 $ 2,182,950 Construction in progress 73,040 78,716 Land and line fill 10,440 10,137 Other 57,548 53,129 Total 2,334,253 2,324,932 Less accumulated depreciation 464,371 442,681 Property, plant and equipment, net $ 1,869,882 $ 1,882,251 In March 2020, in connection with the cancellation of a compressor station project in the DJ Basin due to delays in customer drilling plans, we recorded an impairment charge of $3.6 million for the related soft project costs. In March 2019, certain events occurred which indicated that certain long-lived assets in the DJ Basin and Barnett Shale reporting segments could be impaired. Consequently, in the first quarter of 2019, we performed a recoverability assessment of certain assets within these reporting segments. Also in March 2019, in the DJ Basin we determined that certain processing plant assets related to our existing 20 MMcf/d plant would no longer be utilized due to our expansion plans for the Niobrara G&P system. Based on the results of the recoverability assessment and the conclusion that the carrying value was not fully recoverable, we recorded an impairment charge of $34.7 million related to these assets in the first quarter of 2019. In March 2019, in the Barnett Shale we determined that certain compressor station assets would be shut down and decommissioned. As a result, we recorded an impairment charge of $9.7 million related to these assets in the first quarter of 2019. See Note 6 for additional details. Depreciation expense and capitalized interest follow. Three months ended March 31, 2020 2019 (In thousands) Depreciation expense $ 21,661 $ 19,783 Capitalized interest 491 1,915

AMORTIZING INTANGIBLE ASSETS

AMORTIZING INTANGIBLE ASSETS	3 Months Ended
	Mar. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
AMORTIZING INTANGIBLE ASSETS	6. AMORTIZING INTANGIBLE ASSETS Details regarding our intangible assets, all of which are subject to amortization, follow: March 31, 2020 Gross carrying amount Accumulated amortization Net (In thousands) Favorable gas gathering contracts $ 24,195 $ (15,359 ) $ 8,836 Contract intangibles 278,448 (175,973 ) 102,475 Rights-of-way 157,175 (44,410 ) 112,765 Total intangible assets $ 459,818 $ (235,742 ) $ 224,076 December 31, 2019 Gross carrying amount Accumulated amortization Net (In thousands) Favorable gas gathering contracts $ 24,195 $ (15,125 ) $ 9,070 Contract intangibles 278,448 (169,549 ) 108,899 Rights-of-way 157,175 (42,866 ) 114,309 Total intangible assets $ 459,818 $ (227,540 ) $ 232,278 In March 2019, certain events occurred which indicated that certain long-lived assets relating to the Barnett Shale reporting segment could be impaired (see Note 5). In connection with this evaluation, we evaluated the related intangible assets associated therewith for impairment consisting of rights-of-way intangible assets. We concluded the rights-of-way intangible assets were also impaired and, as a result, we recorded an impairment charge of $0.5 million in the first quarter of 2019. We recognized amortization expense in Other revenues as follows: Three months ended March 31, 2020 2019 (In thousands) Amortization expense – favorable gas gathering contracts $ (234 ) $ (389 ) We recognized amortization expense in costs and expenses as follows: Three months ended March 31, 2020 2019 (In thousands) Amortization expense – contract intangibles $ 6,424 $ 6,397 Amortization expense – rights-of-way 1,544 1,547 The estimated aggregate annual amortization expected to be recognized for the remainder of 2020 and each of the four succeeding fiscal years follows. Intangible assets (In thousands) 2020 $ 23,926 2021 28,209 2022 25,142 2023 25,088 2024 14,917

EQUITY METHOD INVESTMENTS

EQUITY METHOD INVESTMENTS	3 Months Ended
	Mar. 31, 2020
Equity Method Investments And Joint Ventures [Abstract]
EQUITY METHOD INVESTMENTS	7. EQUITY METHOD INVESTMENTS Double E In June 2019, we formed Double E in connection with the Double E Project. Effective June 26, 2019, Summit Permian Transmission, a wholly owned and consolidated subsidiary of the Partnership, and an affiliate of Double E’s foundation shipper (the “JV Partner”) During the three months ended March 31, 2020, we made cash investments of $58.0 million in the Double E Project. Upon completion Double E is deemed to be a variable interest entity as defined in GAAP. As of the date of the Double E Agreement, Summit Permian Transmission was not deemed to be the primary beneficiary due to the JV Partner’s voting rights on significant matters. We account for our ownership interest in Double E as an equity method investment because we have significant influence over Double E. Our portion of Double E’s net assets, which was $92.3 million at March 31, 2020, is reported under the caption Investment in equity method investees on the unaudited condensed consolidated balance sheet. For the three months ended March 31, 2020, other than the investment activity noted above, Double E did not have any results of operations given that the Double E Project is currently under development. Ohio Gathering Ohio Gathering owns and operates 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. As of March 31, 2020 and December 31, 2019, our ownership interest in Ohio Gathering was 38.5%. A reconciliation of our Investment in Ohio Gathering, March 31, 2020 $ 271,268 March cash distributions 1,875 Basis difference 223,151 Investment in Ohio Gathering February 29, 2020 $ 496,294 As noted in our 2019 Annual Report, in December 2019 an impairment loss of long-lived assets was recognized by OCC which brought our investment in OCC to zero. As a result, we have not recorded our portion of OCC’s net loss for the three months ended March 31, 2020 in the Income (loss) from equity method investees caption of our unaudited condensed consolidated statements of operations. Summarized statements of operations information for OGC and OCC follow (amounts represent 100% of investee financial information). Three months ended February 29, 2020 Three months ended February 28, 2019 OGC OCC OGC OCC (In thousands) Total revenues $ 30,068 $ 2,727 $ 33,466 $ 2,266 Total operating expenses 25,750 30,855 25,487 2,973 Net income (loss) 4,311 (28,128 ) 7,972 (707 )

DEFERRED REVENUE

DEFERRED REVENUE	3 Months Ended
	Mar. 31, 2020
Revenue From Contract With Customer [Abstract]
DEFERRED REVENUE	8. DEFERRED REVENUE A rollforward of current deferred revenue follows. Utica Shale Williston Basin DJ Basin Piceance Basin Barnett Shale Marcellus Shale Total current (In thousands) Current deferred revenue, January 1, 2020 $ 18 $ 1,933 $ 2,860 $ 7,014 $ 1,630 $ 38 $ 13,493 Additions 2 483 2,123 1,547 396 9 4,560 Less revenue recognized 5 483 1,285 1,544 409 9 3,735 Current deferred revenue, March 31, 2020 $ 15 $ 1,933 $ 3,698 $ 7,017 $ 1,617 $ 38 $ 14,318 A rollforward of noncurrent deferred revenue follows. Utica Shale Williston Basin DJ Basin Piceance Basin Barnett Shale Marcellus Shale Total noncurrent (In thousands) Noncurrent deferred revenue, January 1, 2020 $ 3 $ 3,634 $ 7,589 $ 17,710 $ 9,575 $ 198 $ 38,709 Additions 425 3,522 3,263 1,304 382 — 8,896 Less reclassification to current deferred revenue 2 483 2,123 1,547 396 9 4,560 Noncurrent deferred revenue, March 31, 2020 $ 426 $ 6,673 $ 8,729 $ 17,467 $ 9,561 $ 189 $ 43,045

DEBT

DEBT	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
DEBT	9. DEBT Debt consisted of the following: March 31, 2020 December 31, 2019 (In thousands) Summit Holdings' variable rate senior secured Revolving Credit Facility (3.74% at March 31, 2020 and 4.55% at December 31, 2019) due May 2022 $ 698,000 $ 677,000 Summit Holdings' 5.5% senior unsecured notes due August 2022 300,000 300,000 Less unamortized debt issuance costs (1) (1,521 ) (1,686 ) Summit Holdings' 5.75% senior unsecured notes due April 2025 500,000 500,000 Less unamortized debt issuance costs (1) (4,763 ) (5,015 ) Total long-term debt $ 1,491,716 $ 1,470,299 (1) Issuance costs are being amortized over the life of the notes. Revolving Credit Facility. Summit Holdings has a senior secured revolving credit facility which allows for revolving loans, letters of credit and swingline loans. The Revolving Credit Facility has a $1.25 billion borrowing capacity, matures in May 2022, and includes a $250.0 million accordion feature. As of March 31, 2020, SMLP and the Guarantor Subsidiaries fully and unconditionally and jointly and severally guarantee, and pledge substantially all of their assets in support of, the indebtedness outstanding under the Revolving Credit Facility. 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 0.75% to 1.75% or the adjusted Eurodollar rate, as defined in the credit agreement, plus an applicable margin ranging from 1.75% to 2.75%, with the commitment fee ranging from 0.30% to 0.50% in each case based on our relative leverage at the time of determination. At March 31, 2020, the applicable margin under LIBOR borrowings was 2.75%, the interest rate was 3.74% and the unused portion of the Revolving Credit Facility totaled $542.9 million, subject to a commitment fee of 0.50%, after giving effect to the issuance thereunder of a $9.1 million outstanding but undrawn irrevocable standby letter of credit. Based on covenant limits, our available borrowing capacity under the Revolving Credit Facility as of March 31, 2020 was approximately $120 million. See Note 15 for additional information on our letter of credit. As of March 31, 2020, we had As of and during the three months ended March 31, 2020, we were in compliance with the Revolving Credit Facility's financial covenants. There were Senior Notes. In July 2014, Summit Holdings and its 100 owned finance subsidiary, Finance Corp. (together with Summit Holdings, 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”) as described in the 2019 Annual Report. In February 2017, the Co-Issuers completed a public offering of T he Guarantor Subsidiaries are 100% owned by a subsidiary of SMLP. The Guarantor Subsidiaries and SMLP fully and unconditionally and jointly and severally guarantee the Senior Notes. There are no significant restrictions on the ability of SMLP or Summit Holdings to obtain funds from its subsidiaries by dividend or loan. Finance Corp. has had no assets or operations since inception in 2013. We have no other independent assets or operations. At no time have the Senior Notes been guaranteed by the Co-Issuers. As of and during the three months ended March 3 1 , 20 20 , we were in compliance with the covenants governing our Senior Notes. There were no defaults or events of default during the three months ended March 3 1 , 20 20 .

FINANCIAL INSTRUMENTS

FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2020
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, restricted cash and accounts receivable. We maintain our cash and cash equivalents and restricted cash 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, compression, 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 or other forms of credit assurance 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, restricted cash, accounts receivable and trade accounts payable reported on the unaudited condensed consolidated 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 which can be made at any time prior to January 15, 2022. In November 2019, we and SMP Holdings entered into a second amendment (the “Second Amendment”) to the Contribution Agreement between us and SMP Holdings dated February 25, 2016, as amended. On November 15, 2019, we made a cash payment of $51.75 million and issued 10,714,285 common units to SMP Holdings (the “November 2019 Prepayment”). In addition, the parties reduced the Remaining Consideration due to SMP Holdings by $19.25 million. Following the November 2019 Prepayment, the Remaining Consideration is $180.75 million. The parties also extended the final date by which we are obligated to deliver the Remaining Consideration to January 15, 2022. The Remaining Consideration remains payable to SMP Holdings in (i) cash, (ii) our common units or (iii) a combination of cash and our common units, and interest continues to accrue (and is payable quarterly in cash) at a rate of 8% per annum on any portion of the Remaining Consideration that remains unpaid after March 31, 2020. The form(s) of Remaining Consideration to be delivered by us to SMP Holdings continue to be determinable by us in our sole discretion (see Note 16 for additional information). A summary of the estimated fair value of our debt financial instruments follows. March 31, 2020 December 31, 2019 Carrying value Estimated fair value (Level 2) Carrying value Estimated fair value (Level 2) (In thousands) Summit Holdings 5.5% Senior Notes ($300.0 million principal) $ 298,479 $ 58,875 $ 298,314 $ 266,750 Summit Holdings 5.75% Senior Notes ($500.0 million principal) 495,237 53,125 494,985 382,708 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 March 31, 2020 and December 31, 2019. The use of different market assumptions or valuation methodologies may have a material effect on the estimated fair value of the Senior Notes.

PARTNERS' CAPITAL AND MEZZANINE

PARTNERS' CAPITAL AND MEZZANINE CAPITAL	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
PARTNERS' CAPITAL AND MEZZANINE CAPITAL	11. PARTNERS' CAPITAL AND MEZZANINE CAPITAL A rollforward of the number of preferred limited partner and common limited partner units follows. Series A Preferred Units Common Units Units, December 31, 2019 300,000 93,493,473 Net units issued under the SMLP LTIP — 975,912 Units, March 31, 2020 300,000 94,469,385 GP/IDR Exchange. On March 22, 2019, we cancelled our IDRs and converted our 2% economic GP interest to a non-economic GP interest in exchange for 8,750,000 SMLP common units which were issued to SMP Holdings in the Equity Restructuring. These units had a fair value of $84.5 million as of the transaction date (March 22, 2019). As a result of the Equity Restructuring, the general partner units and IDRs were eliminated, are no longer outstanding, and no longer participate in distributions of cash from SMLP. Energy Capital Partners continues to control the non-economic GP interest in SMLP. Our General Partner held IDRs (through the Equity Restructuring). Our payment of IDRs as reported in distributions to unitholders – general partner in the statement of partners' capital during the three months ended March 31 follow. Three months ended March 31, 2020 2019 (In thousands) IDR payments $ — $ 2,139 For the purposes of calculating net income attributable to our General Partner in the statements of operations and partners' capital, the financial impact of IDRs was recognized in respect of the quarter for which the distributions were declared. For the purposes of calculating distributions Series A Preferred Units. In 2017, we issued 300,000 Series A Preferred Units representing limited partner interests in the Partnership at a price to the public of $1,000 per unit as described in the 2019 Annual Report. Subsidiary Series A Preferred Units. In December 2019, we issued 30,000 Subsidiary Series A Preferred Units representing limited partner interests in Permian Holdco at a price of $1,000 per unit as described in the 2019 Annual Report. During the three months ended March 31, 2020, we issued an additional 35,000 Subsidiary Series A Preferred Units representing limited partner interests in Permian Holdco at a price of $1,000 per unit. We used the net proceeds of $33.9 million (after deducting underwriting discounts and offering expenses) to fund our share of capital expenses associated with the Double E Project. The proceeds associated with the issuance of Subsidiary Series A Preferred Units are classified as restricted cash on the accompanying unaudited condensed consolidated balance sheets in accordance with the underlying agreement with TPG Energy Solutions Anthem, L.P. until the related funding is used for the Double E Project. Cash Distributions Paid and Declared. We paid the following per-unit distributions during the three months ended March 31 Three months ended March 31, 2020 2019 Per-unit distributions to unitholders $ 0.125 $ 0.575 With respect to our Subsidiary Series A Preferred Units relating to the first quarter of 2020, we declared a payment-in-kind ("PIK") of the quarterly distribution, which resulted in the issuance of 907 Subsidiary Series A Preferred Units. This PIK amount equates to a distribution of $13.9433 per Subsidiary Series A Preferred Unit for the first quarter in 2020, or $70 on an annualized basis. In addition, we issued approximately 38 Subsidiary Series A Preferred Units related to the remaining undrawn commitment (as defined in the underlying agreement with TPG Energy Solutions Anthem, L.P.) as of and for the three months ended March 31, 2020.

EARNINGS PER UNIT

EARNINGS PER UNIT	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
EARNINGS PER UNIT	12. EARNINGS PER UNIT The following table details the components of EPU. Three months ended March 31, 2020 2019 (In thousands, except per-unit amounts) Numerator for basic and diluted EPU: Allocation of net income (loss) among limited partner interests: Net income (loss) attributable to limited partners $ 5,309 $ (36,926 ) Less net income attributable to Series A Preferred Units 7,125 7,125 Less net income attributable to Subsidiary Series A Preferred Units 945 — Net loss attributable to common limited partners $ (2,761 ) $ (44,051 ) Denominator for basic and diluted EPU: Weighted-average common units outstanding – diluted 93,675 75,793 Loss per limited partner unit: Common unit – basic $ (0.03 ) $ (0.58 ) Common unit – diluted $ (0.03 ) $ (0.58 ) Nonvested anti-dilutive phantom units excluded from the calculation of diluted EPU 1,889 34

UNIT-BASED AND NONCASH COMPENSA

UNIT-BASED AND NONCASH COMPENSATION	3 Months Ended
	Mar. 31, 2020
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 2020, we granted 3,811,301 phantom units and associated distribution equivalent rights to employees in connection with our annual incentive compensation award cycle. These awards had a grant date fair value of $0.55 and vest ratably over a three-year • In March 2020, we also issued 549,450 common units to our three independent directors in connection with their annual compensation plan. • During the three months ended March 31, 2020, 418,999 phantom units vested. • In March 2020, we increased the number of common units authorized under the SMLP LTIP to 15,000,000 common units and extended the term of the SMLP LTIP for 10 years. • As of March 31, 2020, approximately 6.9 common units remained available for future issuance under the SMLP LTIP.

RELATED-PARTY TRANSACTIONS

RELATED-PARTY TRANSACTIONS	3 Months Ended
	Mar. 31, 2020
Related Party Transactions [Abstract]
RELATED-PARTY TRANSACTIONS	14. RELATED-PARTY TRANSACTIONS Acquisitions. See Notes 1 and 17 of the 2019 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 Third Amended and Restated Agreement of Limited Partnership (the “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 unaudited condensed 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 March 31, 2020 2019 (In thousands) Operation and maintenance expense $ 5,575 $ 7,885 General and administrative expense 7,841 10,830

LEASES, COMMITMENTS AND CONTING

LEASES, COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
LEASES, COMMITMENTS AND CONTINGENCIES	15. LEASES, COMMITMENTS AND CONTINGENCIES Leases. We account for leases in accordance with ASC Topic 842. We and Summit Investments lease and sublease certain office space and equipment under operating leases. We sublease office space for our corporate headquarters in Houston as well as for corporate offices in Dallas, Denver and Atlanta and offices in and around our gathering systems for terms of between three and ten years. We lease and sublease the office space to limit exposure to risks related to ownership, such as fluctuations in real estate prices. In addition, we lease equipment primarily to support our operations in response to the needs of our gathering systems for terms of between three and four years. We and Summit Investments also lease vehicles under finance leases to support our operations in response to the needs of our gathering systems for a term of three years. We only lease from reputable companies and our leased assets are not specialized in our industry. Some of our leases are subject to annual escalations according to the Consumer Price Index (“CPI”). While lease liabilities are not remeasured as a result of changes to the CPI, changes to the CPI are treated as variable lease payments and recognized in the period in which the obligation for those payments was incurred. We have options to extend the lease and sublease terms of certain office space in Texas, Colorado and West Virginia. The beginning of the noncancelable lease and sublease period for these agreements ranges from 2014 to 2020 and the lease and sublease period ends between 2020 and 2028. These lease and sublease agreements contain between one and three options to renew the lease and sublease for a period of between two and five years. As of March 31, 2020, the exercise of the renewal options for these agreements are not reasonably certain and, as a result, the payments associated with these renewals are not included in the measurement of the lease liability and right-of-use (“ROU”) asset. We also have options to extend the lease term of certain compression equipment used at the Summit Utica gathering system. The beginning of the noncancelable lease period for these leases is 2017 and the lease period ends in 2020. In April 2020, we renewed the lease period for periods of one to three years. Our future minimum lease payments are approximately $2.3 million. Our leases do not contain residual value guarantees. In accordance with the provisions in our Revolving Credit Facility, our aggregate finance lease obligations cannot exceed $50 million in any period of twelve consecutive calendar months during the life of such leases. In March 2019, we entered into an agreement with a third party vendor to construct a transmission line to deliver electric power to the new 60 MMcf/d processing plant in the DJ Basin. The project is expected to cost approximately $7.8 million and we made an up-front payment of $3.0 million, which is included in the Property, plant and equipment, net caption on the unaudited condensed consolidated balance sheet. During the second quarter of 2019, we exercised an option to increase the capacity of the transmission line for an additional cost of $4.3 million and we issued an irrevocable standby letter of credit payable to the vendor with an initial term of one year totaling $9.1 million, which reflects the expected remaining cost of the project. The letter of credit will automatically renew for successive twelve-month Our significant assumptions or judgments include the determination of whether a contract contains a lease and the discount rate used in our lease liabilities. The rate implicit in our lease contracts is not readily determinable. In determining the discount rate used in our lease liabilities, we analyzed certain factors in our incremental borrowing rate, including collateral assumptions and the term used. Our incremental borrowing rate on the Revolving Credit Facility was 4.55% at December 31, 2019, which reflects the fixed rate at which we could borrow a similar amount, for a similar term and with similar collateral as in the lease contracts at the commencement date. ROU assets (included in the Property, plant and equipment, net caption on our unaudited condensed consolidated balance sheet) and lease liabilities (included in the Other current liabilities and Other noncurrent liabilities captions on our unaudited condensed consolidated balance sheet) follow: March 31, 2020 December 31, 2019 (In thousands) ROU assets Operating $ 4,306 $ 3,580 Finance 2,649 3,159 $ 6,955 $ 6,739 Lease liabilities, current Operating $ 967 $ 1,221 Finance 1,023 1,246 $ 1,990 $ 2,467 Lease liabilities, noncurrent Operating $ 3,482 $ 2,513 Finance 483 676 $ 3,965 $ 3,189 Lease cost and Other information follow: Three months ended March 31, 2020 2019 (In thousands) Lease cost Finance lease cost: Amortization of ROU assets (included in depreciation and amortization) $ 352 $ 368 Interest on lease liabilities (included in interest expense) 18 23 Operating lease cost (included in general and administrative expense) 772 832 $ 1,142 $ 1,223 Three months ended March 31, 2020 2019 (In thousands) Other information Cash paid for amounts included in the measurement of lease liabilities Operating cash outflows from operating leases $ 708 $ 821 Operating cash outflows from finance leases 18 23 Financing cash outflows from finance leases 417 445 ROU assets obtained in exchange for new operating lease liabilities 1,199 — ROU assets obtained in exchange for new finance lease liabilities — 693 Weighted-average remaining lease term (years) - operating leases 6.0 3.5 Weighted-average remaining lease term (years) - finance leases 2.0 2.0 Weighted-average discount rate - operating leases 5 % 5 % Weighted-average discount rate - finance leases 4 % 4 % We recognize total lease expense incurred or allocated to us in general and administrative expenses. Lease expense related to operating leases, including lease expense incurred on our behalf and allocated to us, was as follows: Three months ended March 31, 2020 2019 (In thousands) Lease expense $ 912 $ 944 Future minimum lease payments due under noncancelable leases for the remainder of 2020 and each of the five succeeding fiscal years and thereafter, were as follows: March 31, 2020 (In thousands) Operating Finance 2020 $ 1,046 $ 873 2021 1,125 606 2022 883 76 2023 741 — 2024 555 — 2025 464 — Thereafter 742 — Total future minimum lease payments $ 5,556 $ 1,555 Future minimum lease payments due under noncancelable leases at December 31, 2019 and each of the five succeeding fiscal years and thereafter, were as follows: December 31, 2019 (In thousands) Operating Finance 2020 $ 1,705 $ 1,299 2021 1,004 616 2022 551 76 2023 408 — 2024 240 — 2025 153 — Thereafter 742 — Total future minimum lease payments $ 4,803 $ 1,991 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 2019 Annual Report, in 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. Total (In thousands) Accrued environmental remediation, January 1, 2020 $ 4,651 Payments made (17 ) Accrued environmental remediation, March 31, 2020 $ 4,634 As of March 31, 2020, 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 March 3 1 , 20 2 1 . 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, unless Summit Investments is unable to pay government fines or its subsidiary, Summit Midstream Partners Holdings, LLC, is unable to honor its indemnity obligations associated with the 2016 sale of Meadowlark Midstream to SMLP. 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.

DISPOSITIONS, DROP DOWN TRANSAC

DISPOSITIONS, DROP DOWN TRANSACTIONS AND RESTRUCTURING	3 Months Ended
	Mar. 31, 2020
Business Combinations [Abstract]
DISPOSITIONS, DROP DOWN TRANSACTIONS AND RESTRUCTURING	16. DISPOSITIONS, DROP DOWN TRANSACTIONS AND RESTRUCTURING Tioga Midstream Disposition. In February 2019, Tioga Midstream, LLC, a subsidiary of SMLP, and certain affiliates of SMLP (collectively, “Summit”) entered into two Purchase and Sale Agreements (the “Tioga PSAs”) with Hess Infrastructure Partners LP and Hess North Dakota Pipelines LLC (collectively, “Hess Infrastructure”), pursuant to which Summit agreed to sell the Tioga Midstream system to Hess Infrastructure for a combined cash purchase price of $90 million, subject to adjustments as provided in the Tioga PSAs (the “Tioga Midstream Sale”). On March 22, 2019, Summit closed the Tioga Midstream Sale and recorded a gain on sale of $0.9 million based on the difference between the consideration received and the carrying value for Tioga Midstream at closing. The gain is included in the Gain on asset sales, net caption on the unaudited condensed consolidated statement of operations. The financial results of Tioga Midstream (a component of the Williston Basin reportable segment) are included in our unaudited condensed consolidated financial statements and footnotes for the period from January 1, 2019 through March 22, 2019. 2016 Drop Down. In 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 Ohio Gathering. The net consideration paid and recognized in connection with the 2016 Drop Down (i) consisted of a cash payment to SMP Holdings of On November 7, 2019, we and SMP Holdings entered into the Second Amendment to the Contribution Agreement between us and SMP Holdings dated February 25, 2016, as amended. On November 15, 2019, we made the November 2019 Prepayment. In addition, the parties reduced the Remaining Consideration due to SMP Holdings by $19.25 million. Following the November 2019 Prepayment, the Remaining Consideration is $180.75 million. The parties also extended the final date by which we are obligated to deliver the Remaining Consideration to January 15, 2022. The Remaining Consideration remains payable to SMP Holdings in (i) cash, (ii) our common units or (iii) a combination of cash and our common units, and interest continues to accrue (and is payable quarterly in cash) at a rate of 8% per annum on any portion of the Remaining Consideration that remains unpaid after March 31, 2020. The form(s) of Remaining Consideration to be delivered by us to SMP Holdings continue to be determinable by us in our sole discretion. As of March 31, 2020, the Remaining Consideration of the Deferred Purchase Price Obligation was $180.75 million on the unaudited condensed consolidated balance sheet. Restructuring Activities. In 2019, our management approved and initiated a plan to restructure our operations resulting in certain management, facility and organizational changes. During the three months ended March 31, 2020, we expensed costs of approximately $2.8 million associated with restructuring activities. These activities consisted primarily of employee-related costs and consulting costs in support of the project. These costs are included within the General and administrative caption on the unaudited condensed consolidated statement of operations. As of March 31, 2020, the components of our restructuring plan are as follows: • Employee-related costs — We reorganized our workforce and eliminated redundant or unneeded positions. In connection with the workforce restructuring, we expect to incur severance, benefits and other employee related costs of approximately $4.1 million over the next nine months following March 31, 2020. During the three months ended March 31, 2020, we expensed approximately $1.9 million primarily related to severance, redundant salaries, certain bonuses and other employee benefits in connection with our plan. As of March 31, 2020, cash payments were made of approximately $2.1 million and we had approximately $2.4 million included in the Other current liabilities caption on the unaudited condensed consolidated balance sheets for these costs, which we expect to pay over the remainder of the year. • Consultants — We engaged third-party consulting firms to assist in the evaluation of the Partnership’s cost structure, to help formulate the plan to implement the project, and to provide project management services for certain project initiatives. During the three months ended March 31, 2020, we expensed approximately $0.9 million related to these services. As of March 31, 2020, cash payments of approximately $1.1 million were made and we had approximately $0.4 million included in the Other current liabilities caption on the unaudited condensed consolidated balance sheets for these costs, which we expect to pay over the remainder of the year. We expect to incur an additional $0.2 million related to consulting costs to be incurred over the next nine months following March 31, 2020

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	3 Months Ended
	Mar. 31, 2020
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	17. SUBSEQUENT EVENTS We have evaluated subsequent events for recognition or disclosure in the unaudited condensed consolidated financial statements and no events have occurred that require recognition or disclosure, except for the following. On May 3, 2020, we entered into a purchase agreement with Energy Capital Partners (“ECP”) and certain of its affiliates (the “Purchase Agreement”) pursuant to which we agreed to acquire Summit Investments in exchange for approximately $35 million in cash and warrants for the purchase of up to an aggregate of 10,000,000 common units (the “GP Buy-In Transaction”). Summit Investments is the sole member of SMP Holdings, which in turn owns (i) our General Partner, (ii) 34,604,581 SMLP common units pledged as collateral under the SMPH Term Loan, (iii) 10,714,285 SMLP common units not pledged as collateral and (iv) the right to receive the Deferred Purchase Price Obligation. The terms of the Purchase Agreement were unanimously approved by the conflicts committee (the “Conflicts Committee”) of the Board of Directors, comprised solely of independent directors, and was unanimously approved by the Board of Directors. The Purchase Agreement contains customary representations and warranties and covenants by each of the parties, and various closing conditions and termination rights, all as detailed in the Partnership’s Current Report on Form 8-K filed with the SEC on May 5, 2020. At the closing of the GP Buy-In Transaction, Summit Holdings, a Delaware limited liability company and wholly owned subsidiary of the Partnership (the “Borrower”), will borrow an aggregate principal amount of $35 million from certain affiliates of ECP pursuant to two separate term loan agreements that will mature on March 31, 2021 (“Term Loan Credit Agreements”), and upon the terms and subject to the other conditions set forth therein (the “Loans”). The Loans under the Term Loan Credit Agreements will bear interest at a rate of 8.00% per annum, and will generally be (i) guaranteed by the Partnership and each subsidiary of the Borrower that guarantees the obligations under the Borrower’s Revolving Credit Facility, and (ii) secured by a first priority lien on and security interest in all property that secures the obligations under the Revolving Credit Facility. The summaries of the Purchase Agreement and the Term Loan Credit Agreements contained in this Quarterly Report on Form 10-Q do not purport to be complete and are qualified in their entirety by reference to the Partnership’s Current Report on Form 8-K filed with the SEC on May 5, 2020. Simultaneously with the execution of the Purchase Agreement, the Partnership immediately suspended its distributions to holders of its common units and suspended payment of distributions to holders of its Series A Preferred Units representing limited partner interests in the Partnership, commencing with respect to the quarter ending March 31, 2020. Upon closing of the GP Buy-In Transaction, all directors affiliated with ECP will resign from the Board of Directors. Going forward, the Board of Directors will consist of a majority of independent directors. Upon the closing of the GP Buy-In Transaction, the Third Amended and Restated Agreement of Limited Partnership of the Partnership will be amended and restated, and the Amended and Restated Limited Liability Company Agreement of the GP will be amended and restated, to, among other things, provide the holders of common units with voting rights in the election of directors of the Board of Directors on a staggered basis beginning in 2022. On April 10, 2020, we received a formal notice from the New York Stock Exchange (“NYSE”) indicating noncompliance with the continued listing standard set forth in Rule 802.01C of the NYSE Listed Company Manual because the average closing price of our common units had fallen below $1.00 per unit over a period of 30 consecutive trading days, which is the minimum average unit price for continued listing on the NYSE. We have six months following the receipt of the formal noncompliance notice to cure the deficiency and regain compliance. During this period, our common units will continue trading on the NYSE under our existing ticker symbol, with the addition of a suffix indicating the "below criteria" status of our common units, as "SMLP.BC." We intend to regain compliance with the NYSE listing standards by pursuing measures which include (i) enhanced capital discipline and operating margins, including a planned 30% reduction in 2020 capital expenditures and ongoing implementation of expense savings initiatives; (ii) debt reduction through capital markets transactions and asset sales; and potentially (iii) consummation of a reverse unit split, subject to approval from our board of directors.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Recent Accounting Pronouncements	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 . We have recently adopted the following accounting pronouncement: • ASU No. 2018-13 Fair Value Measurement (“ASU 2018-13”). ASU 2018-13 updates the disclosure requirements on fair value measurements including new disclosures for the changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. ASU 2018-13 modifies existing disclosures including clarifying the measurement uncertainty disclosure. ASU 2018-13 removes certain existing disclosure requirements including the amount and reasons for transfers between Level 1 and Level 2 fair value measurements and the policy for the timing of transfer between levels. The adoption of ASU 2018-13 on January 1, 2020 did not have a material impact on our unaudited condensed consolidated financial statement disclosures. • ASU No. 2016-13 Financial Instruments – Credit Losses (“ASU 2016-13”). ASU 2016-13 requires the use of a current expected loss model for financial assets measured at amortized cost and certain off-balance sheet credit exposures. Under this model, entities will be required to estimate the lifetime expected credit losses on such instruments based on historical experience, current conditions, and reasonable and supportable forecasts. This amended guidance also expands the disclosure requirements to enable users of financial statements to understand an entity’s assumptions, models and methods for estimating expected credit losses. The changes are effective for annual and interim periods beginning after December 15, 2019, and amendments should be applied using a modified retrospective approach. The adoption of ASU 2016-13 on January 1, 2020 did not have a material impact on our unaudited condensed consolidated financial statements or disclosures. Accounting Pronouncements Pending Adoption • ASU No. 2020-04 Reference Rate Reform (“ASU 2020-04”). ASU 2020-04 provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships and other transactions affected by reference rate reform on financial reporting. The amendments in ASU 2020-04 are effective as of March 12, 2020 through December 31, 2022. We are currently evaluating the provisions of ASU 2020-04 to determine its impact on our unaudited condensed consolidated financial statements and disclosures.
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 revenues and expenses and the disclosure of commitments and contingencies. Further, these estimates and other factors, including those outside of our control, such as the impact of lower commodity prices, may have a significant negative impact to our business, financial condition, results of operations and cash flows. Although management believes these estimates are reasonable, actual results could differ from its estimates. 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 the 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 which are necessary to fairly present the unaudited condensed consolidated balance sheet as of March 31, 2020, the unaudited condensed consolidated statements of operations and statements of partners’ capital for the three months ended March 31, 2020 and 2019 and the unaudited condensed consolidated statements of cash flows for the three months ended March 31, 2020 and 2019. The balance sheet at December 31, 2019 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, 2019, as filed with the SEC on March 9, 2020 (the "2019 Annual Report"). The results of operations for an interim period are not necessarily indicative of results expected for a full year. Risks and Uncertainties. We are closely monitoring the impact of the outbreak of COVID-19 on all aspects of our business, including how it will impact our customers, employees, supply chain and distribution network. While COVID-19 did not have a material adverse effect on our reported results for the first quarter of 2020, only one month of the quarter was affected by COVID-19 and if the current conditions continue, subsequent quarters may reflect these conditions for a full quarter. We are unable to predict the ultimate impact that COVID-19 may have on our business, future results of operations, financial position or cash flows. The full extent to which our operations may be impacted by the COVID-19 pandemic will depend largely on future developments, which are highly uncertain and cannot be accurately predicted, including new information which may emerge concerning the severity of the outbreak and actions by government authorities to contain the outbreak or treat its impact. Furthermore, the impacts of a potential worsening of global economic conditions and the continued disruptions to and volatility in the financial markets remain unknown.

REVENUE (Tables)

REVENUE (Tables)	3 Months Ended
	Mar. 31, 2020
Revenue From Contract With Customer [Abstract]
Schedule of Estimated Revenue Expected to be Recognized and MVC Shortfall Payments	The following table presents estimated revenue expected to be recognized during the remainder of 2020 and over the remaining contract period related to performance obligations that are unsatisfied and are comprised of estimated MVC shortfall payments. We applied the practical expedient in paragraph 606-10-50-14 of ASC Topic 606 for certain arrangements that we consider optional purchases (i.e., there is no enforceable obligation for the customer to make purchases) and those amounts are therefore excluded from the table. 2020 2021 2022 2023 2024 Thereafter (In thousands) Gathering services and related fees $ 86,916 $ 102,127 $ 84,736 $ 66,693 $ 50,608 $ 58,672
Schedule of Disaggregated Revenue by Geographic Area and Major Products and Services Reportable Segments	Revenue by Category. In the following table, revenue is disaggregated by geographic area and major products and services. Ohio Gathering is excluded from the tables below due to equity method accounting. For more detailed information about reportable segments, see Note 4. Reportable Segments Three months ended March 31, 2020 Utica Shale Williston Basin DJ Basin Permian Basin Piceance Basin Barnett Shale Marcellus Shale Total reportable segments All other segments Total (In thousands) Major products / services lines Gathering services and related fees $ 6,962 $ 23,797 $ 6,855 $ 2,311 $ 27,189 $ 10,443 $ 6,235 $ 83,792 $ — $ 83,792 Natural gas, NGLs and condensate sales — 4,324 70 4,512 1,003 3,871 — 13,780 — 13,780 Other revenues — 3,142 1,034 187 1,065 1,260 — 6,688 643 7,331 Total $ 6,962 $ 31,263 $ 7,959 $ 7,010 $ 29,257 $ 15,574 $ 6,235 $ 104,260 $ 643 $ 104,903 Reportable Segments Three months ended March 31, 2019 Utica Shale Williston Basin DJ Basin Permian Basin Piceance Basin Barnett Shale Marcellus Shale Total reportable segments All other segments Total (In thousands) Major products / services lines Gathering services and related fees $ 7,495 $ 25,706 $ 3,724 $ 366 $ 31,840 $ 13,025 $ 6,197 $ 88,353 $ (1,389 ) $ 86,964 Natural gas, NGLs and condensate sales — 5,585 85 4,221 2,302 604 — 12,797 25,131 37,928 Other revenues — 2,908 1,007 32 1,138 1,656 — 6,741 (225 ) 6,516 Total $ 7,495 $ 34,199 $ 4,816 $ 4,619 $ 35,280 $ 15,285 $ 6,197 $ 107,891 $ 23,517 $ 131,408
Schedule of Information about Contract Assets from Contracts with Customers	The following table provides information about contract assets from contracts with customers: March 31, 2020 December 31, 2019 (In thousands) Contract assets, beginning of period $ 3,902 $ 8,755 Additions 13,877 18,077 Transfers out (425 ) (22,930 ) Contract assets, end of period $ 17,354 $ 3,902

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Schedule of assets by reportable segment	Assets by reportable segment follow. March 31, 2020 December 31, 2019 (In thousands) Assets (1): Utica Shale $ 205,341 $ 206,368 Ohio Gathering 271,268 275,000 Williston Basin 452,684 452,152 DJ Basin 200,473 205,308 Permian Basin 184,043 185,708 Piceance Basin 622,403 631,140 Barnett Shale 345,248 350,638 Marcellus Shale 184,279 184,631 Total reportable segment assets 2,465,739 2,490,945 Corporate and Other 159,196 82,506 Total assets $ 2,624,935 $ 2,573,451 (1) At March 31, 2020, Corporate and Other included $92.3 million relating to our investment in Double E (included in the Investment in equity method investees caption of the unaudited condensed consolidated balance sheet). At December 31, 2019, Corporate and Other included $34.7 million relating to our investment in Double E.
Schedule of segment reporting information	Revenues by reportable segment follow. Three months ended March 31, 2020 2019 (In thousands) Revenues (1): Utica Shale $ 6,962 $ 7,495 Williston Basin 31,263 34,199 DJ Basin 7,959 4,816 Permian Basin 7,010 4,619 Piceance Basin 29,257 35,280 Barnett Shale 15,574 15,285 Marcellus Shale 6,235 6,197 Total reportable segments revenue 104,260 107,891 Corporate and Other 643 26,838 Eliminations — (3,321 ) Total revenues $ 104,903 $ 131,408 (1) Excludes revenues earned by Ohio Gathering due to equity method accounting. Depreciation and amortization, including the amortization expense associated with our favorable gas gathering contracts as reported in Other revenues, by reportable segment follows. Three months ended March 31, 2020 2019 (In thousands) Depreciation and amortization (1): Utica Shale $ 1,927 $ 1,908 Williston Basin 6,495 5,436 DJ Basin 1,527 799 Permian Basin 1,345 1,072 Piceance Basin 11,298 11,791 Barnett Shale (2) 4,032 4,330 Marcellus Shale 2,300 2,283 Total reportable segment depreciation and amortization 28,924 27,619 Corporate and Other 939 497 Total depreciation and amortization $ 29,863 $ 28,116 (1) Excludes depreciation and amortization recognized by Ohio Gathering due to equity method accounting. (2) Includes the amortization expense associated with our favorable gas gathering contracts as reported in Other revenues . Cash paid for capital expenditures by reportable segment follow. Three months ended March 31, 2020 2019 (In thousands) Cash paid for capital expenditures (1): Utica Shale $ 909 $ 101 Williston Basin 4,943 8,023 DJ Basin 6,298 28,356 Permian Basin 3,281 7,057 Piceance Basin 346 1,226 Barnett Shale (2) 657 (118 ) Marcellus Shale 422 102 Total reportable segment capital expenditures 16,856 44,747 Corporate and Other 1,727 16,101 Total cash paid for capital expenditures $ 18,583 $ 60,848 (1) Excludes cash paid for capital expenditures by Ohio Gathering due to equity method accounting. (2) For the three months ended March 31, 2019, the amount includes sales tax reimbursements of $1.1 million.
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 March 31, 2020 2019 Percentage of total revenues (1): Counterparty A - Piceance Basin 11 % * (1) 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 March 31, 2020 2019 (In thousands) Reportable segment adjusted EBITDA Utica Shale $ 5,928 $ 6,193 Ohio Gathering 7,939 9,210 Williston Basin 16,192 18,734 DJ Basin 5,911 2,673 Permian Basin 1,581 (550 ) Piceance Basin 23,557 25,999 Barnett Shale 8,760 11,374 Marcellus Shale 5,320 5,142 Total of reportable segments' measures of profit $ 75,188 $ 78,775 A 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 follows. Three months ended March 31, 2020 2019 (In thousands) Reconciliation of income (loss) before income taxes and income (loss) from equity method investees to total of reportable segments' measures of profit: Income (loss) before income taxes and income (loss) from equity method investees $ 1,970 $ (36,266 ) Add: Corporate and Other expense 11,895 14,159 Interest expense 20,218 17,527 Deferred Purchase Price Obligation 2,297 4,427 Depreciation and amortization 29,863 28,116 Proportional adjusted EBITDA for equity method investees 7,939 9,210 Adjustments related to MVC shortfall payments (5,442 ) (4,199 ) Adjustments related to capital reimbursement activity (211 ) (715 ) Unit-based and noncash compensation 2,723 2,526 Loss (gain) on asset sales, net 115 (961 ) Long-lived asset impairment 3,821 44,951 Total of reportable segments' measures of profit $ 75,188 $ 78,775
Schedule of Adjustments Related to Minimum Volume Commitments Shortfall Payments	Adjustments related to MVC shortfall payments by reportable segment follow. Three months ended March 31, 2020 Williston Basin Piceance Basin Barnett Shale Total (In thousands) Adjustments related to expected MVC shortfall payments: $ (5,665 ) $ 223 $ — $ (5,442 ) Three months ended March 31, 2019 Williston Basin Piceance Basin Barnett Shale Total (In thousands) Adjustments related to expected MVC shortfall payments: $ (5,549 ) $ (103 ) $ 1,453 $ (4,199 )

PROPERTY, PLANT, AND EQUIPMEN_2

PROPERTY, PLANT, AND EQUIPMENT, NET (Tables)	3 Months Ended
	Mar. 31, 2020
Property Plant And Equipment [Abstract]
Schedule of property, plant, and equipment, net	Details on property, plant and equipment follow. March 31, 2020 December 31, 2019 (In thousands) Gathering and processing systems and related equipment $ 2,193,225 $ 2,182,950 Construction in progress 73,040 78,716 Land and line fill 10,440 10,137 Other 57,548 53,129 Total 2,334,253 2,324,932 Less accumulated depreciation 464,371 442,681 Property, plant and equipment, net $ 1,869,882 $ 1,882,251
Schedule of depreciation expense and capitalized interest costs	Depreciation expense and capitalized interest follow. Three months ended March 31, 2020 2019 (In thousands) Depreciation expense $ 21,661 $ 19,783 Capitalized interest 491 1,915

AMORTIZING INTANGIBLE ASSETS (T

AMORTIZING INTANGIBLE ASSETS (Tables)	3 Months Ended
	Mar. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible assets and liabilities subject to amortization	Details regarding our intangible assets, all of which are subject to amortization, follow: March 31, 2020 Gross carrying amount Accumulated amortization Net (In thousands) Favorable gas gathering contracts $ 24,195 $ (15,359 ) $ 8,836 Contract intangibles 278,448 (175,973 ) 102,475 Rights-of-way 157,175 (44,410 ) 112,765 Total intangible assets $ 459,818 $ (235,742 ) $ 224,076 December 31, 2019 Gross carrying amount Accumulated amortization Net (In thousands) Favorable gas gathering contracts $ 24,195 $ (15,125 ) $ 9,070 Contract intangibles 278,448 (169,549 ) 108,899 Rights-of-way 157,175 (42,866 ) 114,309 Total intangible assets $ 459,818 $ (227,540 ) $ 232,278
Recognized amortization expense in other revenues and cost and expenses	We recognized amortization expense in Other revenues as follows: Three months ended March 31, 2020 2019 (In thousands) Amortization expense – favorable gas gathering contracts $ (234 ) $ (389 ) We recognized amortization expense in costs and expenses as follows: Three months ended March 31, 2020 2019 (In thousands) Amortization expense – contract intangibles $ 6,424 $ 6,397 Amortization expense – rights-of-way 1,544 1,547
Estimated aggregate annual amortization expected to be recognized	The estimated aggregate annual amortization expected to be recognized for the remainder of 2020 and each of the four succeeding fiscal years follows. Intangible assets (In thousands) 2020 $ 23,926 2021 28,209 2022 25,142 2023 25,088 2024 14,917

EQUITY METHOD INVESTMENTS (Tabl

EQUITY METHOD INVESTMENTS (Tables)	3 Months Ended
	Mar. 31, 2020
Equity Method Investments And Joint Ventures [Abstract]
Equity Method Investments	A reconciliation of our Investment in Ohio Gathering, March 31, 2020 $ 271,268 March cash distributions 1,875 Basis difference 223,151 Investment in Ohio Gathering February 29, 2020 $ 496,294 As noted in our 2019 Annual Report, in December 2019 an impairment loss of long-lived assets was recognized by OCC which brought our investment in OCC to zero. As a result, we have not recorded our portion of OCC’s net loss for the three months ended March 31, 2020 in the Income (loss) from equity method investees caption of our unaudited condensed consolidated statements of operations. Summarized statements of operations information for OGC and OCC follow (amounts represent 100% of investee financial information). Three months ended February 29, 2020 Three months ended February 28, 2019 OGC OCC OGC OCC (In thousands) Total revenues $ 30,068 $ 2,727 $ 33,466 $ 2,266 Total operating expenses 25,750 30,855 25,487 2,973 Net income (loss) 4,311 (28,128 ) 7,972 (707 )

DEFERRED REVENUE (Tables)

DEFERRED REVENUE (Tables)	3 Months Ended
	Mar. 31, 2020
Revenue From Contract With Customer [Abstract]
Rollforward of deferred revenue	A rollforward of current deferred revenue follows. Utica Shale Williston Basin DJ Basin Piceance Basin Barnett Shale Marcellus Shale Total current (In thousands) Current deferred revenue, January 1, 2020 $ 18 $ 1,933 $ 2,860 $ 7,014 $ 1,630 $ 38 $ 13,493 Additions 2 483 2,123 1,547 396 9 4,560 Less revenue recognized 5 483 1,285 1,544 409 9 3,735 Current deferred revenue, March 31, 2020 $ 15 $ 1,933 $ 3,698 $ 7,017 $ 1,617 $ 38 $ 14,318 A rollforward of noncurrent deferred revenue follows. Utica Shale Williston Basin DJ Basin Piceance Basin Barnett Shale Marcellus Shale Total noncurrent (In thousands) Noncurrent deferred revenue, January 1, 2020 $ 3 $ 3,634 $ 7,589 $ 17,710 $ 9,575 $ 198 $ 38,709 Additions 425 3,522 3,263 1,304 382 — 8,896 Less reclassification to current deferred revenue 2 483 2,123 1,547 396 9 4,560 Noncurrent deferred revenue, March 31, 2020 $ 426 $ 6,673 $ 8,729 $ 17,467 $ 9,561 $ 189 $ 43,045

DEBT (Tables)

DEBT (Tables)	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Schedule of debt and capital leases	Debt consisted of the following: March 31, 2020 December 31, 2019 (In thousands) Summit Holdings' variable rate senior secured Revolving Credit Facility (3.74% at March 31, 2020 and 4.55% at December 31, 2019) due May 2022 $ 698,000 $ 677,000 Summit Holdings' 5.5% senior unsecured notes due August 2022 300,000 300,000 Less unamortized debt issuance costs (1) (1,521 ) (1,686 ) Summit Holdings' 5.75% senior unsecured notes due April 2025 500,000 500,000 Less unamortized debt issuance costs (1) (4,763 ) (5,015 ) Total long-term debt $ 1,491,716 $ 1,470,299 (1) Issuance costs are being amortized over the life of the notes.

FINANCIAL INSTRUMENTS (Tables)

FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Summary of the estimated fair value of debt instruments	A summary of the estimated fair value of our debt financial instruments follows. March 31, 2020 December 31, 2019 Carrying value Estimated fair value (Level 2) Carrying value Estimated fair value (Level 2) (In thousands) Summit Holdings 5.5% Senior Notes ($300.0 million principal) $ 298,479 $ 58,875 $ 298,314 $ 266,750 Summit Holdings 5.75% Senior Notes ($500.0 million principal) 495,237 53,125 494,985 382,708

PARTNERS' CAPITAL AND MEZZANI_2

PARTNERS' CAPITAL AND MEZZANINE CAPITAL (Tables)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Schedule of partner units activity	A rollforward of the number of preferred limited partner and common limited partner units follows. Series A Preferred Units Common Units Units, December 31, 2019 300,000 93,493,473 Net units issued under the SMLP LTIP — 975,912 Units, March 31, 2020 300,000 94,469,385
Details of cash distributions	Our General Partner held IDRs (through the Equity Restructuring). Our payment of IDRs as reported in distributions to unitholders – general partner in the statement of partners' capital during the three months ended March 31 follow. Three months ended March 31, 2020 2019 (In thousands) IDR payments $ — $ 2,139 Three months ended March 31, 2020 2019 Per-unit distributions to unitholders $ 0.125 $ 0.575

EARNINGS PER UNIT (Tables)

EARNINGS PER UNIT (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Schedule of earnings per limited partner unit	The following table details the components of EPU. Three months ended March 31, 2020 2019 (In thousands, except per-unit amounts) Numerator for basic and diluted EPU: Allocation of net income (loss) among limited partner interests: Net income (loss) attributable to limited partners $ 5,309 $ (36,926 ) Less net income attributable to Series A Preferred Units 7,125 7,125 Less net income attributable to Subsidiary Series A Preferred Units 945 — Net loss attributable to common limited partners $ (2,761 ) $ (44,051 ) Denominator for basic and diluted EPU: Weighted-average common units outstanding – diluted 93,675 75,793 Loss per limited partner unit: Common unit – basic $ (0.03 ) $ (0.58 ) Common unit – diluted $ (0.03 ) $ (0.58 ) Nonvested anti-dilutive phantom units excluded from the calculation of diluted EPU 1,889 34

RELATED-PARTY TRANSACTIONS (Tab

RELATED-PARTY TRANSACTIONS (Tables)	3 Months Ended
	Mar. 31, 2020
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 March 31, 2020 2019 (In thousands) Operation and maintenance expense $ 5,575 $ 7,885 General and administrative expense 7,841 10,830

LEASES, COMMITMENTS AND CONTI_2

LEASES, COMMITMENTS AND CONTINGENCIES (Tables)	3 Months Ended
	Mar. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Schedule of right-of-use assets and lease liabilities	ROU assets (included in the Property, plant and equipment, net caption on our unaudited condensed consolidated balance sheet) and lease liabilities (included in the Other current liabilities and Other noncurrent liabilities captions on our unaudited condensed consolidated balance sheet) follow: March 31, 2020 December 31, 2019 (In thousands) ROU assets Operating $ 4,306 $ 3,580 Finance 2,649 3,159 $ 6,955 $ 6,739 Lease liabilities, current Operating $ 967 $ 1,221 Finance 1,023 1,246 $ 1,990 $ 2,467 Lease liabilities, noncurrent Operating $ 3,482 $ 2,513 Finance 483 676 $ 3,965 $ 3,189
Schedule of lease cost and other information	Lease cost and Other information follow: Three months ended March 31, 2020 2019 (In thousands) Lease cost Finance lease cost: Amortization of ROU assets (included in depreciation and amortization) $ 352 $ 368 Interest on lease liabilities (included in interest expense) 18 23 Operating lease cost (included in general and administrative expense) 772 832 $ 1,142 $ 1,223 Three months ended March 31, 2020 2019 (In thousands) Other information Cash paid for amounts included in the measurement of lease liabilities Operating cash outflows from operating leases $ 708 $ 821 Operating cash outflows from finance leases 18 23 Financing cash outflows from finance leases 417 445 ROU assets obtained in exchange for new operating lease liabilities 1,199 — ROU assets obtained in exchange for new finance lease liabilities — 693 Weighted-average remaining lease term (years) - operating leases 6.0 3.5 Weighted-average remaining lease term (years) - finance leases 2.0 2.0 Weighted-average discount rate - operating leases 5 % 5 % Weighted-average discount rate - finance leases 4 % 4 %
Schedule of total rent expense related to operating leases	We recognize total lease expense incurred or allocated to us in general and administrative expenses. Lease expense related to operating leases, including lease expense incurred on our behalf and allocated to us, was as follows: Three months ended March 31, 2020 2019 (In thousands) Lease expense $ 912 $ 944
Future minimum lease payments due and future minimum rentals to be received under noncancelable leases and subleases	Future minimum lease payments due under noncancelable leases for the remainder of 2020 and each of the five succeeding fiscal years and thereafter, were as follows: March 31, 2020 (In thousands) Operating Finance 2020 $ 1,046 $ 873 2021 1,125 606 2022 883 76 2023 741 — 2024 555 — 2025 464 — Thereafter 742 — Total future minimum lease payments $ 5,556 $ 1,555 Future minimum lease payments due under noncancelable leases at December 31, 2019 and each of the five succeeding fiscal years and thereafter, were as follows: December 31, 2019 (In thousands) Operating Finance 2020 $ 1,705 $ 1,299 2021 1,004 616 2022 551 76 2023 408 — 2024 240 — 2025 153 — Thereafter 742 — Total future minimum lease payments $ 4,803 $ 1,991
Schedule of accrued environmental remediation	A rollforward of the aggregate accrued environmental remediation liabilities follows. Total (In thousands) Accrued environmental remediation, January 1, 2020 $ 4,651 Payments made (17 ) Accrued environmental remediation, March 31, 2020 $ 4,634

ORGANIZATION, BUSINESS OPERAT_2

ORGANIZATION, BUSINESS OPERATIONS AND PRESENTATION AND CONSOLIDATION - Narrative (Details) - shares	Mar. 31, 2020	Dec. 31, 2019
Organization And Business Operations [Line Items]
Common limited partner capital (shares)	94,469,385	93,493,473
SMP Holdings | Common units
Organization And Business Operations [Line Items]
Common limited partner capital (shares)	45,318,866
Energy Capital Partners | Common units
Organization And Business Operations [Line Items]
Common limited partner capital (shares)	5,915,827

REVENUE - Narrative1 (Details)

REVENUE - Narrative1 (Details)	Mar. 31, 2020
Maximum | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-04-01
Revenue From Contract With Customer [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, Period	25 years

REVENUE - Narrative (Details)

REVENUE - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Revenue From Contract With Customer [Line Items]
Revenue, performance obligation, description of payment terms	Our services are typically billed on a monthly basis and we do not offer extended payment terms. We do not have contracts with financing components.
Receivables with customers	$ 58,000		$ 90,400
Contract assets included in accounts receivable	17,354		$ 3,902	$ 8,755
Gathering Services and Related Fees
Revenue From Contract With Customer [Line Items]
Contract liabilities, revenue	$ 2,400	$ 2,700

REVENUE - Schedule of Estimated

REVENUE - Schedule of Estimated Revenue Expected to be Recognized and MVC Shortfall Payments (Details) - Gathering Services and Related Fees $ in Thousands	Mar. 31, 2020USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, Period	9 months
Revenue, remaining performance obligation	$ 86,916
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, Period	1 year
Revenue, remaining performance obligation	$ 102,127
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, Period	1 year
Revenue, remaining performance obligation	$ 84,736
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, Period	1 year
Revenue, remaining performance obligation	$ 66,693
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, Period	1 year
Revenue, remaining performance obligation	$ 50,608
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, Period
Revenue, remaining performance obligation	$ 58,672

REVENUE - Schedule of Disaggreg

REVENUE - Schedule of Disaggregated Revenue by Geographic Area and Major Products and Services Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation Of Revenue [Line Items]
Total revenues	$ 104,903	$ 131,408
All Other Segments
Disaggregation Of Revenue [Line Items]
Total revenues	643	23,517
Reportable Segments
Disaggregation Of Revenue [Line Items]
Total revenues	104,260	107,891
Reportable Segments | Utica Shale
Disaggregation Of Revenue [Line Items]
Total revenues	6,962	7,495
Reportable Segments | Williston Basin
Disaggregation Of Revenue [Line Items]
Total revenues	31,263	34,199
Reportable Segments | DJ Basin
Disaggregation Of Revenue [Line Items]
Total revenues	7,959	4,816
Reportable Segments | Permian Basin
Disaggregation Of Revenue [Line Items]
Total revenues	7,010	4,619
Reportable Segments | Piceance Basin
Disaggregation Of Revenue [Line Items]
Total revenues	29,257	35,280
Reportable Segments | Barnett Shale
Disaggregation Of Revenue [Line Items]
Total revenues	15,574	15,285
Reportable Segments | Marcellus Shale
Disaggregation Of Revenue [Line Items]
Total revenues	6,235	6,197
Gathering Services and Related Fees
Disaggregation Of Revenue [Line Items]
Total revenues	83,792	86,964
Gathering Services and Related Fees | All Other Segments
Disaggregation Of Revenue [Line Items]
Total revenues	0	(1,389)
Gathering Services and Related Fees | Reportable Segments
Disaggregation Of Revenue [Line Items]
Total revenues	83,792	88,353
Gathering Services and Related Fees | Reportable Segments | Utica Shale
Disaggregation Of Revenue [Line Items]
Total revenues	6,962	7,495
Gathering Services and Related Fees | Reportable Segments | Williston Basin
Disaggregation Of Revenue [Line Items]
Total revenues	23,797	25,706
Gathering Services and Related Fees | Reportable Segments | DJ Basin
Disaggregation Of Revenue [Line Items]
Total revenues	6,855	3,724
Gathering Services and Related Fees | Reportable Segments | Permian Basin
Disaggregation Of Revenue [Line Items]
Total revenues	2,311	366
Gathering Services and Related Fees | Reportable Segments | Piceance Basin
Disaggregation Of Revenue [Line Items]
Total revenues	27,189	31,840
Gathering Services and Related Fees | Reportable Segments | Barnett Shale
Disaggregation Of Revenue [Line Items]
Total revenues	10,443	13,025
Gathering Services and Related Fees | Reportable Segments | Marcellus Shale
Disaggregation Of Revenue [Line Items]
Total revenues	6,235	6,197
Natural Gas, NGLs and Condensate Sales
Disaggregation Of Revenue [Line Items]
Total revenues	13,780	37,928
Natural Gas, NGLs and Condensate Sales | All Other Segments
Disaggregation Of Revenue [Line Items]
Total revenues	0	25,131
Natural Gas, NGLs and Condensate Sales | Reportable Segments
Disaggregation Of Revenue [Line Items]
Total revenues	13,780	12,797
Natural Gas, NGLs and Condensate Sales | Reportable Segments | Utica Shale
Disaggregation Of Revenue [Line Items]
Total revenues	0	0
Natural Gas, NGLs and Condensate Sales | Reportable Segments | Williston Basin
Disaggregation Of Revenue [Line Items]
Total revenues	4,324	5,585
Natural Gas, NGLs and Condensate Sales | Reportable Segments | DJ Basin
Disaggregation Of Revenue [Line Items]
Total revenues	70	85
Natural Gas, NGLs and Condensate Sales | Reportable Segments | Permian Basin
Disaggregation Of Revenue [Line Items]
Total revenues	4,512	4,221
Natural Gas, NGLs and Condensate Sales | Reportable Segments | Piceance Basin
Disaggregation Of Revenue [Line Items]
Total revenues	1,003	2,302
Natural Gas, NGLs and Condensate Sales | Reportable Segments | Barnett Shale
Disaggregation Of Revenue [Line Items]
Total revenues	3,871	604
Natural Gas, NGLs and Condensate Sales | Reportable Segments | Marcellus Shale
Disaggregation Of Revenue [Line Items]
Total revenues	0	0
Other Revenues
Disaggregation Of Revenue [Line Items]
Total revenues	7,331	6,516
Other Revenues | All Other Segments
Disaggregation Of Revenue [Line Items]
Total revenues	643	(225)
Other Revenues | Reportable Segments
Disaggregation Of Revenue [Line Items]
Total revenues	6,688	6,741
Other Revenues | Reportable Segments | Utica Shale
Disaggregation Of Revenue [Line Items]
Total revenues	0	0
Other Revenues | Reportable Segments | Williston Basin
Disaggregation Of Revenue [Line Items]
Total revenues	3,142	2,908
Other Revenues | Reportable Segments | DJ Basin
Disaggregation Of Revenue [Line Items]
Total revenues	1,034	1,007
Other Revenues | Reportable Segments | Permian Basin
Disaggregation Of Revenue [Line Items]
Total revenues	187	32
Other Revenues | Reportable Segments | Piceance Basin
Disaggregation Of Revenue [Line Items]
Total revenues	1,065	1,138
Other Revenues | Reportable Segments | Barnett Shale
Disaggregation Of Revenue [Line Items]
Total revenues	1,260	1,656
Other Revenues | Reportable Segments | Marcellus Shale
Disaggregation Of Revenue [Line Items]
Total revenues	$ 0	$ 0

REVENUE - Schedule of Informati

REVENUE - Schedule of Information about Contract Assets from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Contract With Customer Asset And Liability [Abstract]
Contract assets, beginning of period	$ 3,902	$ 8,755
Additions	13,877	18,077
Transfers out	(425)	(22,930)
Contract assets, end of period	$ 17,354	$ 3,902

SEGMENT INFORMATION - Assets, R

SEGMENT INFORMATION - Assets, Revenues, Depreciation and Amortization, and Capital Expenditures by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Assets	$ 2,624,935		$ 2,573,451
Revenues	104,903	$ 131,408
Depreciation and amortization	29,863	28,116
Capital expenditures	18,583	60,848
Reportable Segments
Segment Reporting Information [Line Items]
Assets	2,465,739		2,490,945
Revenues	104,260	107,891
Depreciation and amortization	28,924	27,619
Capital expenditures	16,856	44,747
Reportable Segments | Utica Shale
Segment Reporting Information [Line Items]
Assets	205,341		206,368
Revenues	6,962	7,495
Depreciation and amortization	1,927	1,908
Capital expenditures	909	101
Reportable Segments | Ohio Gathering
Segment Reporting Information [Line Items]
Assets	271,268		275,000
Reportable Segments | Williston Basin
Segment Reporting Information [Line Items]
Assets	452,684		452,152
Revenues	31,263	34,199
Depreciation and amortization	6,495	5,436
Capital expenditures	4,943	8,023
Reportable Segments | DJ Basin
Segment Reporting Information [Line Items]
Assets	200,473		205,308
Revenues	7,959	4,816
Depreciation and amortization	1,527	799
Capital expenditures	6,298	28,356
Reportable Segments | Barnett Shale
Segment Reporting Information [Line Items]
Assets	345,248		350,638
Revenues	15,574	15,285
Depreciation and amortization	4,032	4,330
Capital expenditures	657	(118)
Reportable Segments | Permian Basin
Segment Reporting Information [Line Items]
Assets	184,043		185,708
Revenues	7,010	4,619
Depreciation and amortization	1,345	1,072
Capital expenditures	3,281	7,057
Reportable Segments | Marcellus Shale
Segment Reporting Information [Line Items]
Assets	184,279		184,631
Revenues	6,235	6,197
Depreciation and amortization	2,300	2,283
Capital expenditures	422	102
Reportable Segments | Piceance Basin
Segment Reporting Information [Line Items]
Assets	622,403		631,140
Revenues	29,257	35,280
Depreciation and amortization	11,298	11,791
Capital expenditures	346	1,226
Corporate and Other
Segment Reporting Information [Line Items]
Assets	159,196		$ 82,506
Revenues	643	26,838
Depreciation and amortization	939	497
Capital expenditures	$ 1,727	16,101
Eliminations
Segment Reporting Information [Line Items]
Revenues		$ (3,321)

SEGMENT INFORMATION - Narrative

SEGMENT INFORMATION - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Equity method investment	$ 363,578		$ 309,728
Capital expenditures	18,583	$ 60,848
Corporate
Segment Reporting Information [Line Items]
Capital expenditures		300
Corporate and Other
Segment Reporting Information [Line Items]
Capital expenditures	1,727	16,101
Corporate and Other | Double E
Segment Reporting Information [Line Items]
Capital expenditures			$ 34,700
Equity method investment	92,300
Reportable Segments
Segment Reporting Information [Line Items]
Capital expenditures	16,856	44,747
Reportable Segments | Barnett Shale
Segment Reporting Information [Line Items]
Sales tax reimbursement		1,100
Capital expenditures	$ 657	$ (118)

SEGMENT INFORMATION - Concentra

SEGMENT INFORMATION - Concentration Risk (Details)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Sales Revenue, Net | Customer Concentration Risk | Counterparty A - Piceance Basin
Segment Reporting Information [Line Items]
Concentration risk, percentage	11.00%	0.00%

SEGMENT INFORMATION - Adjusted

SEGMENT INFORMATION - Adjusted EBITDA by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 75,188	$ 78,775
Utica Shale
Segment Reporting Information [Line Items]
Adjusted EBITDA	5,928	6,193
Ohio Gathering
Segment Reporting Information [Line Items]
Adjusted EBITDA	7,939	9,210
Williston Basin
Segment Reporting Information [Line Items]
Adjusted EBITDA	16,192	18,734
DJ Basin
Segment Reporting Information [Line Items]
Adjusted EBITDA	5,911	2,673
Permian Basin
Segment Reporting Information [Line Items]
Adjusted EBITDA	1,581	(550)
Piceance Basin
Segment Reporting Information [Line Items]
Adjusted EBITDA	23,557	25,999
Barnett Shale
Segment Reporting Information [Line Items]
Adjusted EBITDA	8,760	11,374
Marcellus Shale
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 5,320	$ 5,142

SEGMENT INFORMATION - Reconcili

SEGMENT INFORMATION - Reconciliation of Net Income (Loss) to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting [Abstract]
Income (loss) before income taxes and income (loss) from equity method investees	$ 1,970	$ (36,266)
Add:
Corporate and Other expense	11,895	14,159
Interest expense	20,218	17,527
Deferred Purchase Price Obligation	2,297	4,427
Depreciation and amortization	29,863	28,116
Proportional adjusted EBITDA for equity method investees	7,939	9,210
Adjustments related to MVC shortfall payments	(5,442)	(4,199)
Adjustments related to capital reimbursement activity	(211)	(715)
Unit-based and noncash compensation	2,723	2,526
Loss (gain) on asset sales, net	115	(961)
Long-lived asset impairment	3,821	44,951
Total of reportable segments' measures of profit	$ 75,188	$ 78,775

SEGMENT INFORMATION - Schedule

SEGMENT INFORMATION - Schedule of Adjustments Related to Minimum Volume Commitments Shortfall Payments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Adjustments related to MVC shortfall payments	$ (5,442)	$ (4,199)
Williston Basin
Segment Reporting Information [Line Items]
Adjustments related to MVC shortfall payments	(5,665)	(5,549)
Piceance Basin
Segment Reporting Information [Line Items]
Adjustments related to MVC shortfall payments	$ 223	(103)
Barnett Shale
Segment Reporting Information [Line Items]
Adjustments related to MVC shortfall payments		$ 1,453

PROPERTY, PLANT, AND EQUIPMEN_3

PROPERTY, PLANT, AND EQUIPMENT, NET - Schedule of Property, Plant, and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 2,334,253	$ 2,324,932
Less accumulated depreciation	464,371	442,681
Property, plant and equipment, net	1,869,882	1,882,251
Gathering and processing systems and related equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,193,225	2,182,950
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	73,040	78,716
Land and line fill
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	10,440	10,137
Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 57,548	$ 53,129

PROPERTY, PLANT, AND EQUIPMEN_4

PROPERTY, PLANT, AND EQUIPMENT, NET - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
DJ Basin
Property, Plant and Equipment [Line Items]
Asset impairment charges	$ 3.6	$ 34.7
Barnett Shale
Property, Plant and Equipment [Line Items]
Asset impairment charges		$ 9.7

PROPERTY, PLANT, AND EQUIPMEN_5

PROPERTY, PLANT, AND EQUIPMENT, NET - Schedule of Depreciation Expense and Capitalized Interest (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Property Plant And Equipment [Abstract]
Depreciation expense	$ 21,661	$ 19,783
Capitalized interest	$ 491	$ 1,915

AMORTIZING INTANGIBLE ASSETS -

AMORTIZING INTANGIBLE ASSETS - Intangible Assets and Liabilities Subject to Amortization (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 459,818	$ 459,818
Accumulated amortization	(235,742)	(227,540)
Net	224,076	232,278
Favorable gas gathering contracts
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	24,195	24,195
Accumulated amortization	(15,359)	(15,125)
Net	8,836	9,070
Contract intangibles
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	278,448	278,448
Accumulated amortization	(175,973)	(169,549)
Net	102,475	108,899
Rights-of-way
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	157,175	157,175
Accumulated amortization	(44,410)	(42,866)
Net	$ 112,765	$ 114,309

AMORTIZING INTANGIBLE ASSETS (N

AMORTIZING INTANGIBLE ASSETS (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Rights-of-way
Finite-Lived Intangible Assets [Line Items]
Impairment charge for intangible assets	$ 0.5

AMORTIZING INTANGIBLE ASSETS _2

AMORTIZING INTANGIBLE ASSETS - Recognized Amortization Expense in Other Revenues and Cost and Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Other Revenue | Favorable gas gathering contracts
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ (234)	$ (389)
Costs And Expenses | Contract intangibles
Finite-Lived Intangible Assets [Line Items]
Amortization expense	6,424	6,397
Costs And Expenses | Rights-of-way
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 1,544	$ 1,547

AMORTIZING INTANGIBLE ASSETS _3

AMORTIZING INTANGIBLE ASSETS - Estimated Aggregate Annual Amortization Expected to be Recognized (Details) $ in Thousands	Mar. 31, 2020USD ($)
Intangible assets
2020	$ 23,926
2021	28,209
2022	25,142
2023	25,088
2024	$ 14,917

EQUITY METHOD INVESTMENTS - Nar

EQUITY METHOD INVESTMENTS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Jun. 26, 2019
Schedule Of Equity Method Investments [Line Items]
Additional cash investments	$ 58,000		$ 18,300
Investment in equity method investees	363,578		$ 309,728
Income (loss) from equity method investees	3,311	$ (441)
Principal Owner
Schedule Of Equity Method Investments [Line Items]
Cash distribution to partnership	7,300
Double E
Schedule Of Equity Method Investments [Line Items]
Asset contribution to an equity method investment	350,000
Parental maximum guaranty for capital calls not met by summit permian transmission				$ 350,000
Remaining capital contributions	$ 251,000
Percentage of ownership interest	50.00%
Net assets	$ 92,300
Result of operations	0
Double E | Principal Owner
Schedule Of Equity Method Investments [Line Items]
Asset contribution to an equity method investment	$ 23,600
Percentage of ownership interest	70.00%
Double E | JV Partner
Schedule Of Equity Method Investments [Line Items]
Percentage of ownership interest	30.00%
Cash contribution	$ 7,300
OGC | Principal Owner
Schedule Of Equity Method Investments [Line Items]
Percentage of ownership interest	38.50%		38.50%
OCC
Schedule Of Equity Method Investments [Line Items]
Investment in equity method investees	$ 0
Income (loss) from equity method investees	$ 0

EQUITY METHOD INVESTMENTS - Rol

EQUITY METHOD INVESTMENTS - Rollforward of the Investment in Equity Method Investees (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2020	Mar. 31, 2019
Schedule Of Equity Method Investments [Line Items]
Investment in Ohio Gathering, March 31, 2020	$ 363,578	$ 363,578
March cash distributions		7,494	$ 8,583
Investment in Ohio Gathering February 29, 2020		309,728
OGC | Summit Midstream Partners, LLC
Schedule Of Equity Method Investments [Line Items]
Investment in Ohio Gathering, March 31, 2020	271,268	$ 271,268
March cash distributions	1,875
Basis difference	223,151
Investment in Ohio Gathering February 29, 2020	$ 496,294

EQUITY METHOD INVESTMENTS - Sta

EQUITY METHOD INVESTMENTS - Statements of Operations Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Feb. 29, 2020	Feb. 28, 2019
OGC
Schedule Of Equity Method Investments [Line Items]
Total revenues	$ 30,068	$ 33,466
Total operating expenses	25,750	25,487
Net income (loss)	4,311	7,972
OCC
Schedule Of Equity Method Investments [Line Items]
Total revenues	2,727	2,266
Total operating expenses	30,855	2,973
Net income (loss)	$ (28,128)	$ (707)

DEFERRED REVENUE - Rollforward

DEFERRED REVENUE - Rollforward of deferred revenue (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	$ 13,493
Current deferred revenue, Additions	4,560
Current deferred revenue, Less revenue recognized	3,735
Current deferred revenue, ending balance	14,318
Noncurrent deferred revenue, beginning balance	38,709
Noncurrent deferred revenue, Additions	8,896
Noncurrent deferred revenue, Less reclassification to current deferred revenue	4,560
Noncurrent deferred revenue, ending balance	43,045
Utica Shale
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	18
Current deferred revenue, Additions	2
Current deferred revenue, Less revenue recognized	5
Current deferred revenue, ending balance	15
Noncurrent deferred revenue, beginning balance	3
Noncurrent deferred revenue, Additions	425
Noncurrent deferred revenue, Less reclassification to current deferred revenue	2
Noncurrent deferred revenue, ending balance	426
Williston Basin
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	1,933
Current deferred revenue, Additions	483
Current deferred revenue, Less revenue recognized	483
Current deferred revenue, ending balance	1,933
Noncurrent deferred revenue, beginning balance	3,634
Noncurrent deferred revenue, Additions	3,522
Noncurrent deferred revenue, Less reclassification to current deferred revenue	483
Noncurrent deferred revenue, ending balance	6,673
Piceance Basin
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	7,014
Current deferred revenue, Additions	1,547
Current deferred revenue, Less revenue recognized	1,544
Current deferred revenue, ending balance	7,017
Noncurrent deferred revenue, beginning balance	17,710
Noncurrent deferred revenue, Additions	1,304
Noncurrent deferred revenue, Less reclassification to current deferred revenue	1,547
Noncurrent deferred revenue, ending balance	17,467
DJ Basin
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	2,860
Current deferred revenue, Additions	2,123
Current deferred revenue, Less revenue recognized	1,285
Current deferred revenue, ending balance	3,698
Noncurrent deferred revenue, beginning balance	7,589
Noncurrent deferred revenue, Additions	3,263
Noncurrent deferred revenue, Less reclassification to current deferred revenue	2,123
Noncurrent deferred revenue, ending balance	8,729
Barnett Shale
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	1,630
Current deferred revenue, Additions	396
Current deferred revenue, Less revenue recognized	409
Current deferred revenue, ending balance	1,617
Noncurrent deferred revenue, beginning balance	9,575
Noncurrent deferred revenue, Additions	382
Noncurrent deferred revenue, Less reclassification to current deferred revenue	396
Noncurrent deferred revenue, ending balance	9,561
Marcellus Shale
Movement in Deferred Revenue [Roll Forward]
Current deferred revenue, beginning balance	38
Current deferred revenue, Additions	9
Current deferred revenue, Less revenue recognized	9
Current deferred revenue, ending balance	38
Noncurrent deferred revenue, beginning balance	198
Noncurrent deferred revenue, Additions	0
Noncurrent deferred revenue, Less reclassification to current deferred revenue	9
Noncurrent deferred revenue, ending balance	$ 189

DEBT - Components of Long-Term

DEBT - Components of Long-Term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Total long-term debt	$ 1,491,716	$ 1,470,299
SMP Holdings
Line of Credit Facility [Line Items]
Total long-term debt	1,491,716	1,470,299
SMP Holdings | Senior Secured Revolving Credit Facility Due May 2022
Line of Credit Facility [Line Items]
Revolving credit facility	698,000	677,000
SMP Holdings | Senior Notes Due August 2022
Line of Credit Facility [Line Items]
Unsecured notes	300,000	300,000
Less unamortized debt issuance costs	(1,521)	(1,686)
SMP Holdings | Senior Notes Due April 2025
Line of Credit Facility [Line Items]
Unsecured notes	500,000	500,000
Less unamortized debt issuance costs	$ (4,763)	$ (5,015)

DEBT - Components of Long-Ter_2

DEBT - Components of Long-Term Debt (Parenthetical) (Details) - SMP Holdings	Mar. 31, 2020	Dec. 31, 2019
Senior Secured Revolving Credit Facility Due May 2022
Line of Credit Facility [Line Items]
Variable interest rate	3.74%	4.55%
Senior Notes Due August 2022
Line of Credit Facility [Line Items]
Stated interest rate	5.50%	5.50%
Senior Notes Due April 2025
Line of Credit Facility [Line Items]
Stated interest rate	5.75%	5.75%

DEBT - Revolving Credit Facilit

DEBT - Revolving Credit Facility (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Jun. 30, 2019
Line of Credit Facility [Line Items]
Line of credit facility, outstanding amount		$ 9,100,000
Revolving credit facility
Line of Credit Facility [Line Items]
Borrowing capacity	$ 1,250,000,000
Revolving credit facility maturity date	2022-05
Accordion feature	$ 250,000,000
Commitment fee on unused portion of the facility	0.50%
Interest rate at period end	3.74%
Unused portion under the facility	$ 542,900,000
Line of credit facility, outstanding amount	9,100,000
Current borrowing capacity	120,000,000
Debt issuance costs	5,500,000
Debt defaults	$ 0
Revolving credit facility | LIBOR
Line of Credit Facility [Line Items]
Applicable margin	2.75%
Revolving credit facility | Minimum
Line of Credit Facility [Line Items]
Commitment fee on unused portion of the facility	0.30%
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%
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 (Narrative)

DEBT - Senior Notes (Narrative) (Details) - USD ($)	1 Months Ended
	Nov. 30, 2018	Feb. 28, 2017	Jul. 31, 2014
Guarantor Subsidiaries
Debt Instrument [Line Items]
Cumulative percentage ownership in subsidiary	100.00%
5.75% Senior Notes
Debt Instrument [Line Items]
Stated interest rate		5.75%	5.75%
Maturity date		Apr. 15, 2025
Debt face amount		$ 500,000,000
Summit Holdings and Finance Corporation | Senior Notes Due August 2022
Debt Instrument [Line Items]
Senior unsecured notes			$ 300,000,000
Stated interest rate			5.50%
Maturity date			Aug. 15, 2022
Finance Corp | Summit Holdings
Debt Instrument [Line Items]
Cumulative percentage ownership in subsidiary			100.00%

FINANCIAL INSTRUMENTS - Concent

FINANCIAL INSTRUMENTS - Concentration Risk - Narrative (Details) - Customer	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
CONCENTRATIONS OF RISK
Number of top customers	5
Five Largest Customers | Accounts Receivable | Customer Concentration Risk
CONCENTRATIONS OF RISK
Concentration risk, percentage	49.00%	46.00%

FINANCIAL INSTRUMENTS - Fair Va

FINANCIAL INSTRUMENTS - Fair Value - Narrative (Details) - Drop Down Assets 2016 Acquisition - USD ($) $ in Thousands	Mar. 31, 2020	Nov. 07, 2019	Mar. 31, 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Payments to Acquire Businesses, Gross		$ 51,750
Business acquisition, reduced amount of consideration		19,250
Remaining cash consideration payable		$ 180,750
Annual accrued Interest rate on unpaid consideration	8.00%		8.00%
Remaining consideration description		the Remaining Consideration is $180.75 million. The parties also extended the final date by which we are obligated to deliver the Remaining Consideration to January 15, 2022. The Remaining Consideration remains payable to SMP Holdings in (i) cash, (ii) our common units or (iii) a combination of cash and our common units, and interest continues to accrue (and is payable quarterly in cash) at a rate of 8% per annum on any portion of the Remaining Consideration that remains unpaid after March 31, 2020.
Common units
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Business acquisition, share issued (shares)		10,714,285

FINANCIAL INSTRUMENTS - Fair _2

FINANCIAL INSTRUMENTS - Fair value of Debt Instruments (Details) - Summit Holdings - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Carrying value | 5.5% Senior Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior notes	$ 298,479	$ 298,314
Carrying value | 5.75% Senior Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior notes	495,237	494,985
Fair Value | 5.5% Senior Notes | Estimated fair value (Level 2)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior notes	58,875	266,750
Fair Value | 5.75% Senior Notes | Estimated fair value (Level 2)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior notes	$ 53,125	$ 382,708

FINANCIAL INSTRUMENTS - Fair _3

FINANCIAL INSTRUMENTS - Fair value of Debt Instruments (Parenthetical) (Details) - Summit Holdings - USD ($)	Mar. 31, 2020	Dec. 31, 2019
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%	5.75%
Debt face amount	$ 500,000,000	$ 500,000,000

PARTNERS' CAPITAL AND MEZZANI_3

PARTNERS' CAPITAL AND MEZZANINE CAPITAL - Partners' Capital and Schedule of Units (Details)	3 Months Ended
	Mar. 31, 2020shares
Series A Preferred Units
Rollforwards of the number of partner units
Units, beginning balance (in shares)	300,000
Units, ending balance (in shares)	300,000
Common Units
Rollforwards of the number of partner units
Units, beginning balance (in shares)	93,493,473
Net units issued under the SMLP LTIP (in shares)	975,912
Units, ending balance (in shares)	94,469,385

PARTNERS' CAPITAL AND MEZZANI_4

PARTNERS' CAPITAL AND MEZZANINE CAPITAL - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 22, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2017
Partners Capital [Line Items]
Fair value			$ 0
Preferred units issued		300,000			300,000
Series A Preferred Units
Partners Capital [Line Items]
Preferred units issued						300,000
Interest in partnership per unit						$ 1,000
Series A Preferred Units | Paid-in-Kind Distributions
Partners Capital [Line Items]
Pro-rated issuance of preferred units		907
Pro-rated distribution of preferred units		$ 13.9433
Pro-rated distribution of preferred units				$ 70
Pro-rated issuance of preferred units related to undrawn commitment		38
Series A Preferred Units | Permian Holdco
Partners Capital [Line Items]
Preferred units issued		35,000			30,000
Interest in partnership per unit		$ 1,000			$ 1,000
Series A Preferred Units | Permian Holdco | Double E
Partners Capital [Line Items]
Proceeds from issuance of common limited partners units		$ 33,900
General Partner
Partners Capital [Line Items]
Fair value			$ (22,222)
GP/IDR Exchange | Summit Midstream Partners, LP | Common units | SMP Holdings
Partners Capital [Line Items]
General partner units converted	8,750,000
Fair value	$ 84,500
GP/IDR Exchange | General Partner | Summit Midstream Partners, LP | SMP Holdings
Partners Capital [Line Items]
General partner interest		2.00%

PARTNERS' CAPITAL AND MEZZANI_5

PARTNERS' CAPITAL AND MEZZANINE CAPITAL - Incentive Distribution Rights (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Equity [Abstract]
IDR payments	$ 2,139

PARTNERS' CAPITAL AND MEZZANI_6

PARTNERS' CAPITAL AND MEZZANINE CAPITAL - Cash Distributions Paid and Declared (Details) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Equity [Abstract]
Per-unit annual distributions to unitholders (in dollars per unit)	$ 0.125	$ 0.575

EARNINGS PER UNIT (Details)

EARNINGS PER UNIT (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Net income (loss) attributable to limited partners	$ 5,309	$ (36,926)
Phantom Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Nonvested anti-dilutive phantom units excluded from the calculation of diluted EPU	1,889	34
Limited Partner Interest Before Subordinated Units Converted To Common Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Net income (loss) attributable to limited partners	$ 5,309	$ (36,926)
Series A Preferred Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Net income (loss) attributable to limited partners	7,125	7,125
Series A Preferred Units | Subsidiary
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Net income (loss) attributable to limited partners	945	0
Common units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Net income (loss) attributable to limited partners	$ (2,761)	$ (44,051)
Diluted (shares)	93,675	75,793
Common unit – basic	$ (0.03)	$ (0.58)
Common unit – diluted	$ (0.03)	$ (0.58)

UNIT-BASED AND NONCASH COMPEN_2

UNIT-BASED AND NONCASH COMPENSATION - Narrative (Details) - SMLP LTIP	1 Months Ended	3 Months Ended
	Mar. 31, 2020Director$ / sharesshares	Mar. 31, 2020shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Units remaining available	6,900,000	6,900,000
Phantom Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted units (in shares)	3,811,301
Grant date fair value (in dollars per share) | $ / shares	$ 0.55
Vesting period	3 years
Issued units (in shares)	549,450
No. of directors | Director	3
Units vested (in shares)		418,999
Number of authorized common units increased	15,000,000
Common units extended term	10 years

RELATED-PARTY TRANSACTIONS - Ex

RELATED-PARTY TRANSACTIONS - Expenses Incurred by the General Partner and Reimbursed (Details) - General Partner - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operation and maintenance expense
RELATED-PARTY TRANSACTIONS
Expenses from transactions with related party	$ 5,575	$ 7,885
General and administrative expense
RELATED-PARTY TRANSACTIONS
Expenses from transactions with related party	$ 7,841	$ 10,830

LEASES, COMMITMENTS AND CONTI_3

LEASES, COMMITMENTS AND CONTINGENCIES - Narrative (Details)	1 Months Ended	3 Months Ended		12 Months Ended
	Mar. 31, 2019USD ($)MMcf	Mar. 31, 2020USD ($)Agreement	Jun. 30, 2019USD ($)	Dec. 31, 2019
Loss Contingencies [Line Items]
Finance leases, term of contract		3 years
Lessee, operating lease, existence of residual value guarantee [true false]		false
Lessee, operating lease, residual value guarantee, Description		Our leases do not contain residual value guarantees.
Lessee, operating lease, assumptions and judgments, whether contract is or contains lease		Our significant assumptions or judgments include the determination of whether a contract contains a lease and the discount rate used in our lease liabilities.
Lessee, operating lease, assumptions and judgments, discount rate, description		The rate implicit in our lease contracts is not readily determinable. In determining the discount rate used in our lease liabilities, we analyzed certain factors in our incremental borrowing rate, including collateral assumptions and the term used. Our incremental borrowing rate on the Revolving Credit Facility was 4.55% at December 31, 2019, which reflects the fixed rate at which we could borrow a similar amount, for a similar term and with similar collateral as in the lease contracts at the commencement date.
Electric power | MMcf	60
Cost of project	$ 7,800,000
Up front payment included in property, plant and equipment	$ 3,000,000
Additional cost to increase transmission line capacity			$ 4,300,000
Letter of credit initial term			1 year
Irrevocable letter of credit payable			$ 9,100,000
Letter of credit renew term			12 months
Revolving credit facility
Loss Contingencies [Line Items]
Finance operating Lease obligations not exceed consolidated total assets		$ 50,000,000
Percentage of operating lease incremental borrowing rate				4.55%
Irrevocable letter of credit payable		$ 9,100,000
Office Space
Loss Contingencies [Line Items]
Lessee, operating lease, existence of option to extend [true false]		true
Lessee, operating lease, option to extend		We have options to extend the lease and sublease terms of certain office space in Texas, Colorado and West Virginia. The beginning of the noncancelable lease and sublease period for these agreements ranges from 2014 to 2020 and the lease and sublease period ends between 2020 and 2028. These lease and sublease agreements contain between one and three options to renew the lease and sublease for a period of between two and five years. As of March 31, 2020, the exercise of the renewal options for these agreements are not reasonably certain and, as a result, the payments associated with these renewals are not included in the measurement of the lease liability and right-of-use (“ROU”) asset.
Equipment
Loss Contingencies [Line Items]
Lessee, operating lease, option to extend		We also have options to extend the lease term of certain compression equipment used at the Summit Utica gathering system. The beginning of the noncancelable lease period for these leases is 2017 and the lease period ends in 2020. In April 2020, we renewed the lease period for periods of one to three years. Our future minimum lease payments are approximately $2.3 million.
Minimum [Member] | Office Space
Loss Contingencies [Line Items]
Operating leases, term of contract		3 years
Operating lease, number of renewal terms | Agreement		1
Lease agreements renewal periods		2 years
Minimum [Member] | Equipment
Loss Contingencies [Line Items]
Operating leases, term of contract		3 years
Maximum | Meadowlark Midstream Gathering System | Principal Owner
Loss Contingencies [Line Items]
Coverage from pollution liability insurance policy		$ 25,000,000
Coverage from property and business interruption insurance policy		$ 200,000,000
Maximum | Office Space
Loss Contingencies [Line Items]
Operating leases, term of contract		10 years
Operating lease, number of renewal terms | Agreement		3
Lease agreements renewal periods		5 years
Maximum | Equipment
Loss Contingencies [Line Items]
Operating leases, term of contract		4 years

LEASES, COMMITMENTS AND CONTI_4

LEASES, COMMITMENTS AND CONTINGENCIES - Schedule of Right of Use Assets and Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Right-of-use asset	$ 4,306	$ 3,580
Finance	2,649	3,159
Total	6,955	6,739
Lease liabilities, current
Operating	967	1,221
Finance	1,023	1,246
Total	1,990	2,467
Lease liabilities, noncurrent
Operating	3,482	2,513
Finance	483	676
Total	$ 3,965	$ 3,189

LEASES, COMMITMENTS AND CONTI_5

LEASES, COMMITMENTS AND CONTINGENCIES - Schedule of Lease Cost and Other Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Lease cost
Amortization of ROU assets (included in depreciation and amortization)	$ 352	$ 368
Interest on lease liabilities (included in interest expense)	18	23
Operating lease cost (included in general and administrative expense)	772	832
Total lease cost	1,142	1,223
Other information
Operating cash outflows from operating leases	708	821
Operating cash outflows from finance leases	18	23
Financing cash outflows from finance leases	417	445
ROU assets obtained in exchange for new operating lease liabilities	$ 1,199
ROU assets obtained in exchange for new finance lease liabilities		$ 693
Weighted-average remaining lease term (years) - operating leases	6 years	3 years 6 months
Weighted-average remaining lease term (years) - finance leases	2 years	2 years
Weighted-average discount rate - operating leases	5.00%	5.00%
Weighted-average discount rate - finance leases	4.00%	4.00%

LEASES, COMMITMENTS AND CONTI_6

LEASES, COMMITMENTS AND CONTINGENCIES - Rent Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Lease expense	$ 912	$ 944

LEASES, COMMITMENTS AND CONTI_7

LEASES, COMMITMENTS AND CONTINGENCIES - Future Minimum Lease Payments Due and Future Minimum Rentals to be Received under Noncancelable Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Operating lease, Future minimum lease payments, 2020	$ 1,046
Operating lease, Future minimum lease payments, 2021	1,125	$ 1,004
Operating lease, Future minimum lease payments, 2022	883	551
Operating lease, Future minimum lease payments, 2023	741	408
Operating lease, Future minimum lease payments, 2024	555	240
Operating lease, Future minimum lease payments, 2025	464	153
Operating lease, Future minimum lease payments, Thereafter	742	742
Operating lease, Total future minimum lease payments	5,556	4,803
Finance lease, Future minimum lease payments, 2020	873
Finance lease, Future minimum lease payments, 2021	606	616
Finance lease, Future minimum lease payments, 2022	76	76
Finance lease, Total future minimum lease payments	$ 1,555	1,991
Operating lease, Future minimum lease payments, 2020		1,705
Finance lease, Future minimum lease payments, 2020		$ 1,299

LEASES, COMMITMENTS AND CONTI_8

LEASES, COMMITMENTS AND CONTINGENCIES - Environmental Matters (Details) - Meadowlark Midstream Gathering System $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Accrual for Environmental Loss Contingencies [Roll Forward]
Accrued environmental remediation, beginning balance	$ 4,651
Payments made	(17)
Accrued environmental remediation, ending balance	$ 4,634

DISPOSITIONS, DROP DOWN TRANS_2

DISPOSITIONS, DROP DOWN TRANSACTIONS AND RESTRUCTURING - Tioga Midstream Disposition (Details) - Tioga Midstream, LLC - Disposal, not discontinued operations - Purchase and Sale Agreement $ in Millions	Mar. 22, 2019USD ($)	Feb. 28, 2019USD ($)Agreement
Business Acquisition [Line Items]
Number of purchase and sale agreements | Agreement		2
Cash purchase price of disposals		$ 90
Gain on sale of business	$ 0.9

DISPOSITIONS, DROP DOWN TRANS_3

DISPOSITIONS, DROP DOWN TRANSACTIONS AND RESTRUCTURING - 2016 Drop Down (Details) - Drop Down Assets 2016 Acquisition - USD ($) $ in Thousands	Mar. 31, 2020	Nov. 07, 2019	Jun. 30, 2016	Mar. 31, 2020	Dec. 31, 2016
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross		$ 51,750
Working capital adjustment			$ 600
Business acquisition, reduced amount of consideration		19,250
Remaining cash consideration payable		$ 180,750
Annual accrued Interest rate on unpaid consideration	8.00%			8.00%
Remaining consideration description		the Remaining Consideration is $180.75 million. The parties also extended the final date by which we are obligated to deliver the Remaining Consideration to January 15, 2022. The Remaining Consideration remains payable to SMP Holdings in (i) cash, (ii) our common units or (iii) a combination of cash and our common units, and interest continues to accrue (and is payable quarterly in cash) at a rate of 8% per annum on any portion of the Remaining Consideration that remains unpaid after March 31, 2020.
Deferred purchase price obligation	$ 180,750			$ 180,750
Revolving credit facility
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross					$ 360,000

DISPOSITIONS, DROP DOWN TRANS_4

DISPOSITIONS, DROP DOWN TRANSACTIONS AND RESTRUCTURING - Restructuring Activities (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Employee Related Costs
Business Acquisition [Line Items]
Restructuring and related cost, expected cost	$ 4.1
Severance costs	1.9
Cash payment	2.1
Employee related cost included in other current liabilities	2.4
Consultants
Business Acquisition [Line Items]
Restructuring costs	0.9
Restructuring and related cost, expected cost	0.2
Cash payment	1.1
Consultant related liabilities current	0.4
General and Administrative Expense
Business Acquisition [Line Items]
Restructuring costs	$ 2.8

SUBSEQUENT EVENTS - Narrative (

SUBSEQUENT EVENTS - Narrative (Details) $ / shares in Units, $ in Millions	May 03, 2020USD ($)shares	Apr. 10, 2020d$ / shares
Subsequent Event
Subsequent Event [Line Items]
Purchase agreement date	May 3, 2020
Closing price of common stock units | $ / shares		$ 1
Number of consecutive days | d		30
Notice period to cure the deficiency and regain compliance		6 months
Plan to reduction in capital expenditures and ongoing implementation of expense, percentage		30.00%
Term Loan Credit Agreements | Scenario Forecast
Subsequent Event [Line Items]
Borrowing capacity | $	$ 35
Maturity date	Mar. 31, 2021
Stated interest rate	8.00%
Line of Credit Facility, Description	The Loans under the Term Loan Credit Agreements will bear interest at a rate of 8.00% per annum, and will generally be (i) guaranteed by the Partnership and each subsidiary of the Borrower that guarantees the obligations under the Borrower’s Revolving Credit Facility, and (ii) secured by a first priority lien on and security interest in all property that secures the obligations under the Revolving Credit Facility
Summit Investments | Subsequent Event
Subsequent Event [Line Items]
Payments to Acquire Businesses, Gross | $	$ 35
Summit Investments | Common units | Subsequent Event
Subsequent Event [Line Items]
Business acquisition, share issued (shares)	10,000,000
SMP Holdings | Subsequent Event
Subsequent Event [Line Items]
SMLP common units pledged as collateral under the SMPH Term Loan	34,604,581
SMLP common units not pledged as collateral under the SMPH Term Loan	10,714,285