Entity Central Index Key Transactions under common control, change in amount of contingent consideration, liability. Corporate and other expenses. Depreciation depletion and amortization including amortization of above and below market leases. Adjusted earnings before interest, taxes, depreciation, and amortization, proportional equity method investment adjustment. Adjustments related to minimum volume commitments shortfall payments. Adjustments related to capital reimbursement activity. Adjusted earnings before interest, taxes, depreciation, and amortization. Deferred revenue, minimum volume commitments shortfall payments, net. Expected minimum volume commitments shortfall adjustments. Contributions To Equity Method Investees Payments for proceeds from advances to affiliates. Early repayment of senior debt one. Payments for proceeds from advances to affiliates. Cover [Abstract] Entity Registrant Name Entity Registrant Name Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Public Float Entity Public Float Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Well-known Seasoned Issuer Entity Well Known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Entity Interactive Data Current Entity Interactive Data Current Title of 12(b) Security Security12b Title Security Exchange Name Security Exchange Name Entity File Number Entity File Number Entity Incorporation, State or Country Code Entity Incorporation State Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address Address Line1 Entity Address, Address Line Two Entity Address Address Line2 Entity Address, City or Town Entity Address City Or Town Entity Address, State or Province Entity Address State Or Province Entity Address, Postal Zip Code Entity Address Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Document Annual Report Document Annual Report Document Transition Report Document Transition Report Statement Of Financial Position [Abstract] Statement [Table] Statement [Table] Equity Components Statement Equity Components [Axis] Equity Component Equity Component [Domain] Mezzanine Capital [Member] Mezzanine Capital Mezzanine Capital [Member] Statement [Line Items] Statement [Line Items] Assets Assets [Abstract] Current assets: Assets Current [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Restricted cash Restricted Cash Accounts receivable Accounts Receivable Net Current Other current assets Other Assets Current Total current assets Assets Current Property, plant and equipment, net Property Plant And Equipment Net Intangible assets, net Finite Lived Intangible Assets Net Goodwill Goodwill Investment in equity method investees Equity Method Investments Other noncurrent assets Other Assets Noncurrent Total assets Assets Liabilities and Capital Liabilities And Stockholders Equity [Abstract] Current liabilities: Liabilities Current [Abstract] Trade accounts payable Accounts Payable Current Accrued expenses Accrued Liabilities Current Due to affiliate Due To Affiliate Current Deferred revenue Contract With Customer Liability Current Ad valorem taxes payable Accrual For Taxes Other Than Income Taxes Current Accrued interest Interest Payable Current Accrued environmental remediation Accrued Environmental Loss Contingencies Current Other current liabilities Other Liabilities Current Total current liabilities Liabilities Current Long-term debt Long Term Debt Noncurrent Noncurrent Deferred Purchase Price Obligation Business Combination Contingent Consideration Liability Noncurrent Noncurrent deferred revenue Contract With Customer Liability Noncurrent Noncurrent accrued environmental remediation Accrued Environmental Loss Contingencies Noncurrent Other noncurrent liabilities Other Liabilities Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 16) Commitments And Contingencies Mezzanine Capital Temporary Equity [Abstract] Subsidiary Series A Preferred Units (30,058 units issued and outstanding at December 31, 2019) Temporary Equity Carrying Amount Attributable To Parent Partners' Capital Partners Capital [Abstract] Series A Preferred Units (300,000 units issued and outstanding at Preferred Units Preferred Partners Capital Accounts Common limited partner capital (93,493,473 units issued and outstanding at December 31, 2019 and 73,390,853 units issued and outstanding at December 31, 2018) Limited Partners Capital Account General Partner interests (zero units issued and outstanding at December 31, 2019 and 1,490,999 units issued and outstanding at December 31, 2018) General Partners Capital Account Total partners' capital Partners Capital Including Portion Attributable To Noncontrolling Interest Total liabilities, mezzanine capital and partners' capital Liabilities And Stockholders Equity Subsidiary Series A preferred unitholders, issued Preferred Units Issued Subsidiary Series A preferred unitholders, outstanding Preferred Units Outstanding Common limited partner capital (in shares), issued Limited Partners Capital Account Units Issued Common limited partner capital (in shares), outstanding Limited Partners Capital Account Units Outstanding General partner interests (in shares), issued General Partners Capital Account Units Issued General partner interests (in shares), outstanding General Partners Capital Account Units Outstanding Net Income Attributable to General Partner Including IDRS. Income Statement [Abstract] Product and Service Product Or Service [Axis] Product and Service Products And Services [Domain] Gathering Services and Related Fees Natural Gas Gathering Transportation Marketing And Processing [Member] Natural Gas, NGLs and Condensate Sales Oil And Condensate [Member] Other Revenues Product And Service Other [Member] Limited Partners' Capital Account by Class Limited Partners Capital Account By Class [Axis] Limited Partners' Capital Account, Class Limited Partners Capital Account Class [Domain] Series A preferred units. Series A Preferred Units Series A Preferred Units [Member] Represents information pertaining to common units issued by the partnership. Common units Common Units [Member] Consolidated Entities Consolidated Entities [Axis] Consolidated Entities Consolidated Entities [Domain] Subsidiary Subsidiaries [Member] Revenues: Revenues [Abstract] Total revenues Revenue From Contract With Customer Excluding Assessed Tax Costs and expenses: Costs And Expenses [Abstract] Cost of natural gas and NGLs Cost Of Goods And Services Sold Type of Cost, Good or Service [Extensible List] Type Of Cost Good Or Service Extensible List Operation and maintenance Utilities Operating Expense Maintenance And Operations General and administrative General And Administrative Expense Depreciation and amortization Depreciation Depletion And Amortization Transaction costs Business Combination Acquisition Related Costs (Gain) loss on asset sales, net Gain Loss On Disposition Of Assets1 Long-lived asset impairment Impairment Of Long Lived Assets To Be Disposed Of Goodwill impairment Goodwill Impairment Loss Total costs and expenses Costs And Expenses Other income (expense) Other Operating Income Expense Net Interest expense Interest Expense Early extinguishment of debt Gains Losses On Extinguishment Of Debt Deferred Purchase Price Obligation Transactions Under Common Control Change In Amount Of Contingent Consideration Liability (Loss) income before income taxes and loss from equity method investees Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments Income tax expense Income Tax Expense Benefit Loss from equity method investees Income Loss From Equity Method Investments Net (loss) income Profit Loss Net income attributable to noncontrolling interest Net Income Loss Attributable To Noncontrolling Interest Net (loss) income attributable to SMLP Net Income Loss Net income attributable to General Partner, including IDRs Net Income Attributable To General Partner Including I D R S Net (loss) income attributable to limited partners Net Income Loss Allocated To Limited Partners (Loss) income per limited partner unit: Earnings Per Limited Partnership Unit [Abstract] Basic (in dollars per share) Net Income Loss Per Outstanding Limited Partnership Unit Basic Net Of Tax Diluted (in dollars per share) Net Income Loss Net Of Tax Per Outstanding Limited Partnership Unit Diluted Weighted-average limited partner units outstanding: Weighted Average Number Of Shares Outstanding [Abstract] Basic (shares) Weighted Average Limited Partnership Units Outstanding Diluted (shares) Weighted Average Limited Partnership Units Outstanding Diluted Profit loss excluding subsidiary income. Partners' capital account tax withholding for unit-based compensation. Partners capital partial settlement. Statement Of Partners Capital [Abstract] Partner Type Partner Type Of Partners Capital Account [Axis] Partner Type of Partners' Capital Account, Name Partner Type Of Partners Capital Account Name [Domain] Limited partner series A preferred units. Limited Partner Series A Preferred Units Limited Partner Series A Preferred Units [Member] Party to a partnership business who has limited liability, categorized under common units. Common Limited Partner Common [Member] General Partner General Partner [Member] Summit Investments' equity in contributed subsidiaries Partner Capital Components [Axis] Partner Capital Components Partner Capital Components [Domain] Noncontrolling interest Noncontrolling Interest [Member] Sale of Stock Subsidiary Sale Of Stock [Axis] Sale of Stock Sale Of Stock Name Of Transaction [Domain] At the market program. At Market Program At Market Program [Member] Restatement Restatement [Axis] Restatement Restatement [Domain] Adjustment Restatement Adjustment [Member] Beginning balance January 1, 2018 impact of Topic 606day 1 adoption Cumulative Effect Of New Accounting Principle In Period Of Adoption Net income (loss) Profit Loss Excluding Subsidiary Income Conversion of General Partner economic interests Partners Capital Account Exchanges And Conversions Distributions to unitholders Partners Capital Account Distributions Unit-based compensation Partners Capital Account Unit Based Compensation Tax withholdings on vested SMLP LTIP awards Partners Capital Account Tax Withholding For Unit Based Compensation Issuance of Series A Preferred Units, net of offering costs Partners Capital Account Sale Of Units Contribution from General Partner Partners Capital Account Contributions Purchase of noncontrolling interest Minority Interest Decrease From Redemptions Other Partners Capital Other DPPO partial settlement Partners Capital Partial Settlement Ending balance Non cash lease expense. Write​ off​ of deferred​ debt​ issuance​ cost 1. Cash advances from (to) affiliate to (from) contributed subsidiaries. Proceeds from expense contributions. Transaction under common control, contingent consideration to acquire assets. Excess of acquired carrying value over consideration paid. Distribution of debt to affiliates. Business combination, excess of carrying value over consideration paid. Capitalized interest allocated to affiliates. Statement Of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided By Used In Operating Activities [Abstract] Net (loss) income Adjustments to reconcile net (loss) income to net cash provided by operating activities: Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Depreciation and amortization Depreciation Depletion And Amortization Including Amortization Of Above And Below Market Leases Noncash lease expense Non Cash Lease Expense Amortization of debt issuance costs Amortization Of Financing Costs Deferred Purchase Price Obligation Unit-based and noncash compensation Share Based Compensation Loss from equity method investees Distributions from equity method investees Equity Method Investment Dividends Or Distributions (Gain) loss on asset sales, net Early extinguishment of debt Write-off of debt issuance costs Write Off Of Deferred Debt Issuance Cost1 Changes in operating assets and liabilities: Increase Decrease In Operating Capital [Abstract] Accounts receivable Increase Decrease In Accounts Receivable Trade accounts payable Increase Decrease In Accounts Payable Trade Accrued expenses Increase Decrease In Accrued Liabilities Due from (to) affiliate Increase Decrease In Due To Affiliates Current Deferred revenue, net Increase Decrease In Contract With Customer Liability Ad valorem taxes payable Increase Decrease In Property And Other Taxes Payable Accrued interest Increase Decrease In Interest Payable Net Accrued environmental remediation, net Increase Decrease In Regulatory Liabilities Other, net Increase Decrease In Other Operating Capital Net Net cash provided by operating activities Net Cash Provided By Used In Operating Activities Cash flows from investing activities: Net Cash Provided By Used In Investing Activities [Abstract] Capital expenditures Payments To Acquire Property Plant And Equipment Proceeds from asset sale (net of cash of $1,475 for the year ended December 31, 2019) Proceeds From Sale Of Productive Assets Contributions to equity method investees Contributions To Equity Method Investees Distributions from equity method investment Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital Investment in equity method investee Payments To Acquire Equity Method Investments Purchase of noncontrolling interest Payments To Acquire Additional Interest In Subsidiaries Other, net Payments For Proceeds From Other Investing Activities Net cash used in investing activities Net Cash Provided By Used In Investing Activities Cash flows from financing activities: Net Cash Provided By Used In Financing Activities [Abstract] Distributions to unitholders Distribution Made To Limited Partner Cash Distributions Paid Borrowings under Revolving Credit Facility Proceeds From Long Term Lines Of Credit Repayments under Revolving Credit Facility Repayments Of Lines Of Credit Repayments under term loan Repayments Of Medium Term Notes Repayment of Deferred Purchase Price Obligation Repayments Of Notes Payable Debt issuance costs Payments Of Financing Costs Payment of redemption and call premiums on senior notes Early Repayment Of Senior Debt1 Proceeds from ATM Program common unit issuances, net of costs Proceeds From Sale Of Interest In Partnership Unit Proceeds from underwritten issuance of common units, net of costs Proceeds From Issuance Of Common Limited Partners Units Proceeds from issuance of Series A Preferred Units, net of costs Proceeds From Issuance Of Preferred Limited Partners Units Contribution from General Partner Proceeds From Partnership Contribution Cash advance from Summit Investments to contributed subsidiaries, net Cash Advances From To Affiliate To From Contributed Subsidiaries Expenses paid by Summit Investments on behalf of contributed subsidiaries Proceeds From Expense Contributions Issuance of senior notes Proceeds From Issuance Of Senior Long Term Debt Tender and redemption of senior notes Repayments Of Senior Debt Other, net Proceeds From Payments For Other Financing Activities Net cash used in financing activities Net Cash Provided By Used In Financing Activities Net change in cash, cash equivalents and restricted cash Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect Cash and cash equivalents, beginning of period Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Cash and cash equivalents, end of period Supplemental cash flow disclosures: Supplemental Cash Flow Information [Abstract] Cash interest paid Interest Paid Less capitalized interest Interest Paid Capitalized Interest paid (net of capitalized interest) Interest Paid Net Noncash investing and financing activities Noncash Investing And Financing Items [Abstract] Capital expenditures in trade accounts payable (period-end accruals) Capital Expenditures Incurred But Not Yet Paid Issuance of Deferred Purchase Price Obligation to affiliate to partially fund the 2016 Drop Down Transaction Under Common Control Contingent Consideration To Acquire Assets Excess of acquired carrying value over consideration paid and recognized for 2016 Drop Down Assets Excess Of Acquired Carrying Value Over Consideration Paid Distribution of debt related to Carve-Out Financial Statements of Summit Investments Distribution Of Debt To Affiliates Excess of acquired carrying value over consideration paid for Polar and Divide Business Combination Excessof Carrying Valueover Consideration Paid Capitalized interest allocated to contributed subsidiaries from Summit Investments Capitalized Interest Allocated To Affiliates Proceeds from gain on sale of disposition of assets. Net of cash Proceeds From Gain On Sale Of Disposition Of Assets Capital expenditures relating to contributions in aid of construction. Non cash or part non cash right of use of assets. Cash paid for taxes Income Taxes Paid Asset contribution to an equity method investment Contribution Of Property Capital expenditures relating to contributions in aid of construction for Topic 606 day 1 adoption Capital Expenditures Relating To Contributions In Aid Of Construction Right-of-use assets relating to Topic 842 Non Cash Or Part Non Cash Right Of Use Of Assets Cash and cash equivalents Cash Equivalents At Carrying Value Total cash, cash equivalents and restricted cash Organization Consolidation And Presentation Of Financial Statements [Abstract] ORGANIZATION, BUSINESS OPERATIONS AND PRESENTATION AND CONSOLIDATION Organization Consolidation And Presentation Of Financial Statements Disclosure [Text Block] Accounting Policies [Abstract] SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Significant Accounting Policies [Text Block] Revenue From Contract With Customer [Abstract] REVENUE Revenue From Contract With Customer [Text Block] Segment Reporting [Abstract] SEGMENT INFORMATION Segment Reporting Disclosure [Text Block] Property Plant And Equipment [Abstract] PROPERTY, PLANT, AND EQUIPMENT, NET Property Plant And Equipment Disclosure [Text Block] Goodwill And Intangible Assets Disclosure [Abstract] AMORTIZING INTANGIBLE ASSETS Intangible Assets Disclosure [Text Block] GOODWILL Goodwill Disclosure [Text Block] Equity Method Investments And Joint Ventures [Abstract] EQUITY METHOD INVESTMENTS Equity Method Investments Disclosure [Text Block] Contract with customer liability disclosure. DEFERRED REVENUE Contract With Customer Liability Disclosure [Text Block] Debt Disclosure [Abstract] DEBT Debt Disclosure [Text Block] Fair Value Disclosures [Abstract] FINANCIAL INSTRUMENTS Fair Value Disclosures [Text Block] Equity [Abstract] PARTNERS' CAPITAL AND MEZZANINE CAPITAL Partners Capital Notes Disclosure [Text Block] Earnings Per Share [Abstract] EARNINGS PER UNIT Earnings Per Share [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] UNIT-BASED AND NONCASH COMPENSATION Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Related Party Transactions [Abstract] RELATED-PARTY TRANSACTIONS Related Party Transactions Disclosure [Text Block] Leases, commitments and contingencies. Commitments And Contingencies Disclosure [Abstract] LEASES, COMMITMENTS AND CONTINGENCIES Leases Commitments And Contingencies Disclosure [Text Block] Business Combinations [Abstract] DISPOSITIONS, DROP DOWN TRANSACTIONS AND RESTRUCTURING Business Combination Disclosure [Text Block] Condensed consolidating financial information. Condensed Consolidating Financial Information [Abstract] CONDENSED CONSOLIDATING FINANCIAL INFORMATION Condensed Financial Statements [Text Block] Quarterly Financial Information Disclosure [Abstract] UNAUDITED QUARTERLY FINANCIAL DATA Quarterly Financial Information [Text Block] Subsequent Events [Abstract] SUBSEQUENT EVENTS Subsequent Events [Text Block] Cash, Cash Equivalents and Restricted Cash Cash And Cash Equivalents Restricted Cash And Cash Equivalents Policy Accounts Receivable Trade And Other Accounts Receivable Policy Property, Plant and Equipment Property Plant And Equipment Policy [Text Block] Asset Retirement Obligations Asset Retirement Obligations Policy Intangible assets and noncurrent liabilities policy. Amortizing Intangibles Intangible Assetsand Noncurrent Liabilities Policy Policy [Text Block] Goodwill Goodwill And Intangible Assets Goodwill Policy Equity Method Investments Equity Method Investments Policy Other Noncurrent Assets Deferred Charges Policy [Text Block] Debt Issuance Costs Debt Policy [Text Block] Deferred purchase price obligation income or expense. Deferred Purchase Price Obligation Deferred Purchase Price Obligation Incomeor Expense Policy [Text Block] Impairment of Long-Lived Assets Impairment Or Disposal Of Long Lived Assets Policy [Text Block] Derivative Contracts Derivatives Policy [Text Block] Restructuring costs policy text block. Restructuring Cost Restructuring Costs Policy [Text Block] Fair Value of Financial Instruments Fair Value Of Financial Instruments Policy Commitments and Contingencies Commitments And Contingencies Policy [Text Block] Noncontrolling Interest Consolidation Policy [Text Block] Revenue Recognition Revenue From Contract With Customer Policy [Text Block] Unit-Based Compensation Share Based Compensation Option And Incentive Plans Policy Income Taxes Income Tax Policy [Text Block] Earnings or Loss Per Unit Earnings Per Share Policy [Text Block] Environmental Matters Regulatory Environmental Costs Policy Recent Accounting Pronouncements New Accounting Pronouncements Policy Policy [Text Block] Basis of Presentation Basis Of Accounting Policy Policy [Text Block] Schedule of property plant and equipment useful life. Useful lives of Property, Plant and Equipment Schedule Of Property Plant And Equipment Useful Life Table [Text Block] Schedule of Estimated Revenue Expected to be Recognized and MVC Shortfall Payments Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Table [Text Block] Schedule of Disaggregated Revenue by Geographic Area and Major Products and Services Reportable Segments Disaggregation Of Revenue Table [Text Block] Schedule of contract with customer, asset. Schedule of Contract with Customer Asset Schedule Of Contract With Customer Asset Table [Text Block] Schedule of assets by reportable segment Reconciliation Of Assets From Segment To Consolidated [Text Block] Schedule of segment reporting information Reconciliation Of Revenue From Segments To Consolidated [Text Block] Schedule of counterparties accounting for more than 10% of total revenues Schedules Of Concentration Of Risk By Risk Factor [Text Block] Reconciliation of net income to adjusted EBITDA. Reconciliation of net income to adjusted EBITDA Reconciliation Of Net Income To Adjusted E B I T D A Table [Text Block] Schedule of adjustments related to minimum volume commitments shortfall payments. Schedule of Adjustments Related to Minimum Volume Commitments Shortfall Payments Schedule Of Adjustments Related To Minimum Volume Commitments Shortfall Payments Table [Text Block] Schedule of property, plant, and equipment, net Property Plant And Equipment [Text Block] Schedule of long-lived asset impairments Details Of Impairment Of Long Lived Assets Held And Used By Asset [Text Block] Tabular disclosure of depreciation expense related to the property, plant and equipment and capitalized interest costs. Schedule of depreciation expense and capitalized interest costs Schedule Of Depreciation Expense And Capitalized Interest Costs Table [Text Block] Intangible assets and liabilities subject to amortization Schedule Of Finite Lived Intangible Assets Table [Text Block] Tabular disclosure of amortization income or expense recognized during the period on finite-lived intangible assets and noncurrent liability. Recognized amortization expense in other revenues and cost and expenses Schedule Of Recognized Amortization Income Expense Table [Text Block] Estimated aggregate annual amortization expected to be recognized Scheduleof Finite Lived Intangible Assets Future Amortization Expense Table [Text Block] Rollforward of goodwill by reportable segment Schedule Of Goodwill [Text Block] Equity Method Investments Equity Method Investments [Text Block] Rollforward of deferred revenue Contract With Customer Asset And Liability Table [Text Block] Schedule of debt and capital leases Schedule Of Debt Instruments [Text Block] Schedule of maturities of long-term debt Schedule Of Maturities Of Long Term Debt Table [Text Block] Summary of the estimated fair value of debt instruments Schedule Of Carrying Values And Estimated Fair Values Of Debt Instruments Table [Text Block] Schedule of partner units activity. Schedule of partner units activity Schedule Of Partner Units Activity Table [Text Block] Details of cash distributions Distributions Made To Limited Partner By Distribution Table [Text Block] Schedule of earnings per limited partner unit Schedule Of Earnings Per Share Basic And Diluted Table [Text Block] Schedule of activity Schedule Of Share Based Compensation Activity Table [Text Block] Schedule of intrinsic values Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Table [Text Block] Schedule of unit-based compensation recognized in general and administrative expense Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Text Block] Schedule of related party transactions Schedule Of Related Party Transactions Table [Text Block] Lease assets and liabilities. Schedule of right-of-use assets and lease liabilities Lease Assets And Liabilities Table [Text Block] Schedule of lease cost and other information Lease Cost Table [Text Block] Schedule of total rent expense related to operating leases Schedule Of Rent Expense Table [Text Block] Schedule of future minimum rental payments for finance and operating leases and sublease income. Future minimum lease payments due and future minimum rentals to be received under noncancelable leases and subleases Schedule Of Future Minimum Rental Payments For Finance And Operating Leases And Sublease Income Table [Text Block] Future minimum lease payments due under noncancelable operating leases Schedule Of Future Minimum Rental Payments For Operating Leases Table [Text Block] Schedule of Future Payments Due Under Finance Leases Schedule Of Capital Leased Asssets Table [Text Block] Schedule of accrued environmental remediation Schedule Of Environmental Loss Contingencies By Site [Text Block] Condensed Balance Sheet Schedule Of Condensed Balance Sheet Table [Text Block] Condensed Income Statement Schedule Of Condensed Income Statement Table [Text Block] Condensed Cash Flow Statement Schedule Of Condensed Cash Flow Statement Table [Text Block] Quarterly Summarized Information on Consolidated Results of Operations Schedule Of Quarterly Financial Information Table [Text Block] Organization and business operations. Disclosure pertaining to organization and business operations. Organization And Business Operations [Table] Organization And Business Operations [Table] Legal Entity Legal Entity [Axis] Entity Entity [Domain] Summit Midstream Partners Holdings, LLC. SMP Holdings Summit Midstream Partners Holdings L L C [Member] Summit investments. Summit Investments Summit Investments [Member] Energy Capital Partners. Energy Capital Partners Energy Capital Partners [Member] Ownership Ownership [Axis] Ownership Ownership [Domain] Summit Midstream Partners, LP. Summit Midstream Partners, LP Summit Midstream Partners L P [Member] Organization And Business Operations [Line Items] Organization And Business Operations [Line Items] Common limited partner capital (shares) General partner interest Limited Liability Company L L C Or Limited Partnership L P Managing Member Or General Partner Ownership Interest General partner units converted Partners Capital Account Units Converted Schedule Of Property Plant And Equipment [Table] Schedule Of Property Plant And Equipment [Table] Property, Plant and Equipment, Type Property Plant And Equipment By Type [Axis] Property, Plant and Equipment, Type Property Plant And Equipment Type [Domain] Gathering and processing systems and related equipment Gas Gathering And Processing Equipment [Member] Other Other Capitalized Property Plant And Equipment [Member] Statistical Measurement Range [Axis] Statistical Measurement Range [Member] Minimum Minimum [Member] Maximum Maximum [Member] Property, Plant and Equipment [Line Items] Property Plant And Equipment [Line Items] Useful life Property Plant And Equipment Useful Life Summary of significant accounting policies. Summary of significant accounting policies. Summary Of Significant Accounting Policies [Table] Summary Of Significant Accounting Policies [Table] Finite-Lived Intangible Assets by Major Class Finite Lived Intangible Assets By Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name Finite Lived Intangible Assets Major Class Name [Domain] Represents information pertaining to favorable gas gathering contract intangible assets. Favorable gas gathering contracts Favorable Gas Gathering Contract [Member] Other gas gathering contract. Other Gas Gathering Contract Other Gas Gathering Contract [Member] Represents information pertaining to rights-of-way intangible assets. Rights-of-way Rights Of Way [Member] Business Acquisition Business Acquisition [Axis] Business Acquisition, Acquiree Business Acquisition Acquiree [Domain] Drop down assets 2016 acquisition. Drop Down Assets 2016 Acquisition Drop Down Assets2016 Acquisition [Member] Scenario Statement Scenario [Axis] Scenario Scenario Unspecified [Domain] Scenario Forecast Scenario Forecast [Member] Adjustments for New Accounting Pronouncements Adjustments For New Accounting Pronouncements [Axis] Type of Adoption Type Of Adoption [Member] Accounting Standard Update 2016-02 Accounting Standards Update201602 [Member] Summary of Significant Accounting Policies [Line Items] Summary Of Significant Accounting Policies [Line Items] Useful lives (In years) Finite Lived Intangible Asset Useful Life Business combination reduced amount of consideration. Business combination remaining cash consideration payable Annual accrued Interest rate on unpaid consideration. Business combination consideration description. Payments to Acquire Businesses, Gross Payments To Acquire Businesses Gross Business acquisition, share issued (shares) Business Acquisition Equity Interests Issued Or Issuable Number Of Shares Issued Business acquisition, reduced amount of consideration Business Combination Reduced Amount Of Consideration Remaining cash consideration payable Business Combination Remaining Cash Consideration Payable Annual accrued Interest rate on unpaid consideration Annual Accrued Interest Rate On Unpaid Consideration Remaining consideration description Business Combination Consideration Description Long-term, fee-based contracts with original terms, description. Long-term, fee-based contracts with original terms Long Term Fee Based Contracts With Original Terms Description Right-of-use asset Operating Lease Right Of Use Asset Operating Lease, Liability Operating Lease Liability Revenue from contract with customer. Revenue from contract with customer. Revenue From Contract With Customer [Table] Revenue From Contract With Customer [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Start Date [Axis] Revenue From Contract With Customer [Line Items] Revenue From Contract With Customer [Line Items] Revenue, remaining performance obligation, expected timing of satisfaction, Period Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 Balance Sheet Location Balance Sheet Location [Axis] Balance Sheet Location Balance Sheet Location [Domain] Other Noncurrent Assets Other Noncurrent Assets [Member] Gathering services and related fees. Gathering Services and Related Fees Gathering Servicesand Related Fees [Member] Revenue, performance obligation, description of payment terms Revenue Performance Obligation Description Of Payment Terms Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Table] Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Table] Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items] Revenue, remaining performance obligation Revenue Remaining Performance Obligation Disaggregation Of Revenue [Table] Disaggregation Of Revenue [Table] Natural gas, NGLs and condensate sales. Natural Gas, NGLs and Condensate Sales Natural Gas N G L And Condensate Sales [Member] Other products and services. Other Revenues Other Products And Services [Member] Consolidation Items Consolidation Items [Axis] Consolidation Items Consolidation Items [Domain] Reportable Segments Operating Segments [Member] Segments Statement Business Segments [Axis] Segments Segment [Domain] Utica Shale segment. Utica Shale Utica Shale Segment [Member] Williston Basin segment. Williston Basin Williston Basin Segment [Member] DJ Basin. DJ Basin D J Basin Segment [Member] Piceance Basin segment. Piceance Basin Piceance Basin Segment [Member] Permian Basin segment member. Permian Basin Permian Basin Segment [Member] Barnett Shale segment. Barnett Shale Barnett Shale Segment [Member] Marcellus Shale segment. Marcellus Shale Marcellus Shale Segment [Member] All Other Segments All Other Segments [Member] Disaggregation Of Revenue [Line Items] Disaggregation Of Revenue [Line Items] Contract with customer asset, additions. Contract With Customer Asset And Liability [Abstract] Contract assets, beginning of period Contract With Customer Asset Net Additions Contract With Customer Asset Additions Transfers out Contract With Customer Asset Reclassified To Receivable Contract assets, end of period Receivables with customers Unbilled Contracts Receivable Contract assets included in accounts receivable Long-term contract assets included in other noncurrent assets Contract With Customer Asset Net Noncurrent Contract liabilities, revenue Contract With Customer Liability Revenue Recognized Schedule Of Segment Reporting Information By Segment [Table] Schedule Of Segment Reporting Information By Segment [Table] Corporate and Other Corporate Non Segment [Member] Eliminations Intersegment Elimination [Member] Ohio Gathering segment. Ohio Gathering Ohio Gathering Segment [Member] Piceance Basin Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Assets Capital expenditures. Investment, Name Schedule Of Equity Method Investment Equity Method Investee Name [Axis] Investment, Name Equity Method Investee Name [Domain] Double E Pipeline, LLC. Double E Double E Pipeline L L C [Member] Corporate Corporate [Member] Capital Expenditures Capital Expenditures Equity Method Investments Revenues Concentration Risk Benchmark Concentration Risk By Benchmark [Axis] Concentration Risk Benchmark Concentration Risk Benchmark [Domain] Sales Revenue, Net Sales Revenue Net [Member] Concentration Risk Type Concentration Risk By Type [Axis] Concentration Risk Type Concentration Risk Type [Domain] Customer Concentration Risk Customer Concentration Risk [Member] Customer Major Customers [Axis] Customer Name Of Major Customer [Domain] Counterparty A. Counterparty A - Piceance Basin Counterparty A [Member] Counterparty B. Counterparty B - Williston Basin Counterparty B [Member] Counterparty C. Counterparty C - Piceance Basin Counterparty C [Member] Counterparty D. Counterparty D - Barnet Shale Counterparty D [Member] Concentration risk, percentage Concentration Risk Percentage1 Capital expenditures Payments For Proceeds From Productive Assets Sales tax reimbursements. Sales tax reimbursement Sales Tax Reimbursements Adjusted EBITDA Adjusted Earnings Before Interest Taxes Depreciation And Amortization Reconciliation of net Income to EBITDA, additions. Add: Reconciliation Of Net Income To E B I T D A Additions [Abstract] Corporate and Other expense Corporate And Other Expenses Interest expense Proportional adjusted EBITDA for equity method investees Adjusted Earnings Before Interest Taxes Depreciation And Amortization Proportional Equity Method Investment Adjustment Adjustments related to MVC shortfall payments Adjustments Related To Minimum Volume Commitments Shortfall Payments Adjustments related to capital reimbursement activity Adjustments Related To Capital Reimbursement Activity Total of reportable segments' measures of profit Net change in deferred revenue for MVC shortfall payments Deferred Revenue Minimum Volume Commitments Shortfall Payments Net Expected MVC shortfall adjustments Expected Minimum Volume Commitments Shortfall Adjustments Total adjustments related to MVC shortfall payments Construction in progress Construction In Progress [Member] Land and line fill. Land and line fill Landand Line Fill [Member] Property, plant and equipment, gross Property Plant And Equipment Gross Less accumulated depreciation Accumulated Depreciation Depletion And Amortization Property Plant And Equipment Property, plant and equipment, net Red Rock Gathering Company, LLC. Red Rock Gathering Company LLC Red Rock Gathering Company L L C [Member] Long-lived assets impairment charge Cash purchase price of disposals Proceeds From Divestiture Of Businesses And Interests In Affiliates Asset impairment charges Asset Impairment Charges Utica Shale. Utica Shale Utica Shale [Member] Depreciation expense Depreciation Capitalized interest Interest Costs Incurred Capitalized Schedule Of Finite Lived Intangible Assets [Table] Schedule Of Finite Lived Intangible Assets [Table] Represents information pertaining to intangible contract values of the gas gathering agreement. Contract intangibles Contract Intangibles [Member] Finite-Lived Intangible Assets [Line Items] Finite Lived Intangible Assets [Line Items] Gross carrying amount Finite Lived Intangible Assets Gross Accumulated amortization Finite Lived Intangible Assets Accumulated Amortization Net Contract intangible assets and rights-of-way intangible assets. Contract Intangible Assets and Rights-of-Way Intangible Assets Contract Intangible Assets And Rights Of Way Intangible Assets [Member] Impairment charge for intangible assets Impairment Of Intangible Assets Finitelived Income Statement Location Income Statement Location [Axis] Income Statement Location Income Statement Location [Domain] Other revenue. Other Revenue Other Revenue [Member] Costs and expenses. Costs And Expenses Costs And Expenses [Member] Amortization expense Adjustment For Amortization Intangible assets Finite Lived Intangible Assets Future Amortization Expense [Abstract] 2020 Finite Lived Intangible Assets Amortization Expense Next Twelve Months 2021 Finite Lived Intangible Assets Amortization Expense Year Two 2022 Finite Lived Intangible Assets Amortization Expense Year Three 2023 Finite Lived Intangible Assets Amortization Expense Year Four 2024 Finite Lived Intangible Assets Amortization Expense Year Five Schedule Of Goodwill [Table] Schedule Of Goodwill [Table] Reporting Unit Reporting Unit [Axis] Reporting Unit Reporting Unit [Domain] Mountaineer Midstream. Mountaineer Midstream Mountaineer Midstream [Member] Goodwill [Line Items] Goodwill [Line Items] Accumulated goodwill impairment Goodwill Impaired Accumulated Impairment Loss Schedule Of Equity Method Investments [Table] Schedule Of Equity Method Investments [Table] Double E company. Double E Double E Company L L C [Member] Related Party Related Party Transactions By Related Party [Axis] Related Party Related Party [Domain] Principal Owner Principal Owner [Member] JV Partner. JV Partner J V Partner [Member] Ohio Gathering Company, L.L.C. OGC Ohio Gathering Company L L C [Member] Summit Midstream Partners, LLC. Summit Midstream Partners, LLC Summit Midstream Partners L L C [Member] Asset Class Fair Value By Asset Class [Axis] Asset Class Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation By Asset Class [Domain] Long Lived Assets Finite Lived Intangible Assets [Member] Schedule Of Equity Method Investments [Line Items] Schedule Of Equity Method Investments [Line Items] Percentage of ownership interest Equity Method Investment Ownership Percentage Cash distribution to partnership Additional cash investments Payments To Acquire Other Investments Net Assets Assets Net Result of operations Revenues Equity method investment maximum ownership percentage option. Non-affiliated owners, ownership percent. Cost method investment, ownership percentage. Equity method potential ownership interest Equity Method Investment Maximum Ownership Percentage Option Ownership interest value Cost Method Investments Original Cost Cost method ownership interest Cost Method Investment Ownership Percentage Non-affiliated owners' interest percent Non Affiliated Owners Ownership Percent Equity method investment, maximum ownership percentage option, value. Option value Equity Method Investment Maximum Ownership Percentage Option Value Impairment loss Weighted average discount rate percent1. WeightedAverageDiscountRatePercent1 Weighted Average Discount Rate Percent1 Equity method investment, amortization of difference between carrying amount and underlying equity. Equity method investment. Equity Method Investment [Roll Forward] Equity Method Investment Roll Forward Investment in Ohio Gathering, December 31 December cash distributions Loss contingency Loss Contingency Damages Sought Value Basis difference Equity Method Investment Amortizationof Difference Between Carrying Amountand Underlying Equity Investment in equity method investees, net of basis difference, November 30 Ohio condensate company llc. OCC Ohio Condensate Company L L C [Member] Write-off basis difference Equity Method Investment Difference Between Carrying Amount And Underlying Equity Impairment loss Impairment Of Long Lived Assets Held For Use Ohio Condensate Company. OCC Ohio Condensate Company [Member] Current assets Equity Method Investment Summarized Financial Information Current Assets Noncurrent assets Equity Method Investment Summarized Financial Information Noncurrent Assets Total assets Equity Method Investment Summarized Financial Information Assets Current liabilities Equity Method Investment Summarized Financial Information Current Liabilities Noncurrent liabilities Equity Method Investment Summarized Financial Information Noncurrent Liabilities Total liabilities Equity Method Investment Summarized Financial Information Liabilities Total revenues Equity Method Investment Summarized Financial Information Revenue Total operating expenses Equity Method Investment Summarized Financial Information Cost Of Sales Net income (loss) Equity Method Investment Summarized Financial Information Net Income Loss Contract with customer liability current additions. Contract with customer liability current revenue recognized. Deferred Revenue Disclosure [Abstract] Deferred Revenue Arrangement By Type [Table] Deferred Revenue Arrangement By Type [Table] Deferred Revenue Arrangement [Line Items] Deferred Revenue Arrangement [Line Items] Movement in Deferred Revenue [Roll Forward] Change In Contract With Customer Liability [Abstract] Current deferred revenue, beginning balance Current deferred revenue, Additions Contract With Customer Liability Current Additions Current deferred revenue, Less revenue recognized Contract With Customer Liability Current Revenue Recognized Current deferred revenue, ending balance Contract with customer liability noncurrent additions. Contract with customer liability noncurrent reclassification to current. Noncurrent deferred revenue, beginning balance Noncurrent deferred revenue, Additions Contract With Customer Liability Noncurrent Additions Noncurrent deferred revenue, Less reclassification to current deferred revenue Contract With Customer Liability Noncurrent Reclassification To Current Noncurrent deferred revenue, ending balance Line Of Credit Facility [Table] Line Of Credit Facility [Table] Debt Instrument Debt Instrument [Axis] Debt Instrument, Name Debt Instrument Name [Domain] Senior notes due may twenty twenty two. Senior Secured Revolving Credit Facility Due May 2022 Senior Notes Due May Twenty Twenty Two [Member] Senior notes due August twenty twenty two. Senior Notes Due August 2022 Senior Notes Due August Twenty Twenty Two [Member] Senior notes due April twenty twenty five. Senior Notes Due April 2025 Senior Notes Due April Twenty Twenty Five [Member] Line of Credit Facility [Line Items] Line Of Credit Facility [Line Items] Revolving credit facility Secured Long Term Debt Unsecured notes Unsecured Long Term Debt Less unamortized debt issuance costs Deferred Finance Costs Net Total long-term debt Variable interest rate Line Of Credit Facility Interest Rate At Period End Stated interest rate Debt Instrument Interest Rate Stated Percentage Debt Long Term Debt By Maturity [Abstract] 2020 Long Term Debt Maturities Repayments Of Principal In Next Twelve Months 2021 Long Term Debt Maturities Repayments Of Principal In Year Two 2022 Long Term Debt Maturities Repayments Of Principal In Year Three 2023 Long Term Debt Maturities Repayments Of Principal In Year Four 2024 Long Term Debt Maturities Repayments Of Principal In Year Five Thereafter Long Term Debt Maturities Repayments Of Principal After Year Five Total long-term debt Long Term Debt Line of credit facility, accordion feature, increase limit. Debt covenant ratio of indebtedness to net capital senior secured. Line of credit facility maturity date month and year. Credit Facility Credit Facility [Axis] Credit Facility Credit Facility [Domain] Revolving credit facility Revolving Credit Facility [Member] Variable Rate Variable Rate [Axis] Variable Rate Variable Rate [Domain] Alternate base rate. ABR Alternate Base Rate [Member] LIBOR London Interbank Offered Rate L I B O R [Member] Borrowing capacity Line Of Credit Facility Maximum Borrowing Capacity Revolving credit facility maturity date Line Of Credit Facility Maturity Date Month And Year Accordion feature Line Of Credit Facility Accordion Feature Increase Limit Leverage ratio Ratio Of Indebtedness To Net Capital1 Senior secured leverage ratio Debt Covenant Ratio Of Indebtedness To Net Capital Senior Secured Applicable margin Debt Instrument Basis Spread On Variable Rate1 Commitment fee on unused portion of the facility Line Of Credit Facility Unused Capacity Commitment Fee Percentage Interest rate at period end Unused portion under the facility Line Of Credit Facility Remaining Borrowing Capacity Line of credit facility, outstanding amount Line Of Credit Cumulative Payment Obligations, Maximum Ratio of consolidated trailing 12month EBITDA to net interest expense. Ratio of net indebtedness to consolidated trailing 12 month EBITDA. Ratio of first lien net indebtedness to consolidated trailing 12 month EBITDA. Cumulative payment obligations, maximum Cumulative Payment Obligations Maximum Ratio of consolidated trailing 12-month EBITDA to net interest expense Ratio Of Consolidated Trailing12month E B I T D A To Net Interest Expense Ratio of total net indebtedness to consolidated trailing 12-month EBITDA Ratio Of Net Indebtedness To Consolidated Trailing12 Month E B I T D A Ratio of first lien net indebtedness to consolidated trailing 12-month EBITDA Ratio Of First Lien Net Indebtedness To Consolidated Trailing12 Month E B I T D A Debt issuance costs Deferred Finance Costs Gross Debt defaults Debt Default Longterm Debt Amount Debt Instrument [Table] Debt Instrument [Table] Finance Corp. Finance Corp Finance Corp [Member] Represents information pertaining to Summit Midstream Holdings, LLC, a wholly-owned subsidiary of the reporting entity. Summit Holdings Summit Midstream Holdings L L C [Member] Summit Holdings and Finance Corporation. Summit Holdings and Finance Corporation Summit Holdings And Finance Corporation [Member] 5.5% Senior Notes Five point seven five percent senior notes. 5.75% Senior Notes Five Point Seven Five Percent Senior Notes [Member] Guarantor Subsidiaries Guarantor Subsidiaries [Member] Subsidiary of Summit Investments. Subsidiary of Summit Investments Subsidiary Of Summit Investments [Member] Summit Midstream OpCo Limited Partnership. Summit Midstream OpCo, LP Summit Midstream Op Co Limited Partnership [Member] Seven point five percent senior notes. 7.5% Senior Notes Seven Point Five Percent Senior Notes [Member] 7.5% Senior Notes Debt Instrument, Redemption, Period Debt Instrument Redemption Period [Axis] Debt Instrument, Redemption, Period Debt Instrument Redemption Period [Domain] Redemption period one Debt Instrument Redemption Period One [Member] Redemption period two Debt Instrument Redemption Period Two [Member] Redemption period three Debt Instrument Redemption Period Three [Member] 5.75% Senior Notes Five point five percent senior notes. 5.5% Senior Notes Five Point Five Percent Senior Notes [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Cumulative percentage ownership in subsidiary Subsidiary Or Equity Method Investee Cumulative Percentage Ownership After All Transactions Senior unsecured notes Senior Notes Maturity date Debt Instrument Maturity Date Ownership interest Minority Interest Ownership Percentage By Noncontrolling Owners Redemption and call premiums Gains Losses On Extinguishment Of Debt Before Write Off Of Deferred Debt Issuance Cost Extinguishment of debt Extinguishment Of Debt Amount Percent of principal redeemed Debt Instrument Redemption Price Percentage Of Principal Amount Redeemed Redemption price, expressed as percentage of principal amount Debt Instrument Redemption Price Percentage Deferred issuance costs Debt instrument, event of default, default payment period. Debt instrument, event of default, notice of compliance period. Debt instrument, final judgment amount. Debt instrument, event of default, percent of principal held. Default period Debt Instrument Event Of Default Default Payment Period Compliance notice period Debt Instrument Event Of Default Notice Of Compliance Period Final judgment Debt Instrument Final Judgment Amount Percent of principal (at least) Debt Instrument Event Of Default Percent Of Principal Held Debt issuance costs Deferred Finance Costs Noncurrent Gross Debt instrument, redemption, events of default, period of payment default. Debt instrument, redemption, events of default, failure to comply with covenants, period after notice. Debt instrument, redemption, events of default, failure to comply with other indenture agreements, period after notice. Debt instrument, redemption, events of default, failure to pay final judgments, amount in excess. Debt instrument, redemption, events of default, declaration of immediate payment, minimum holding percentage of principal amount required. Events of default, period of payment default Debt Instrument Redemption Events Of Default Period Of Payment Default Events of default, failure to comply with covenants, period after notice Debt Instrument Redemption Events Of Default Failure To Comply With Covenants Period After Notice Events of default, failure to comply with other agreements in the indenture, period after notice Debt Instrument Redemption Events Of Default Failure To Comply With Other Indenture Agreements Period After Notice Events of default, failure to pay final judgments, in excess of 20.0 million Debt Instrument Redemption Events Of Default Failure To Pay Final Judgments Amount In Excess Declaration of immediate payment, holding percent of principal amount required Debt Instrument Redemption Events Of Default Declaration Of Immediate Payment Minimum Holding Percentage Of Principal Amount Required Number of top customers. Concentration Risk [Table] Concentration Risk [Table] Five largest customers. Five Largest Customers Five Largest Customers [Member] Accounts receivable Accounts Receivable [Member] CONCENTRATIONS OF RISK Concentration Risk [Line Items] Number of top customers Number Of Top Customers Fair Value By Balance Sheet Grouping [Table] Fair Value By Balance Sheet Grouping [Table] Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items] Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items] Measurement Basis Fair Value By Measurement Basis [Axis] Fair Value Disclosure Item Amounts [Default] Portion At Fair Value Fair Value Disclosure [Member] Fair Value Measurement Fair Value Disclosure Item Amounts [Domain] Carrying value Carrying Reported Amount Fair Value Disclosure [Member] Fair Value Estimate Of Fair Value Fair Value Disclosure [Member] Senior Notes due 2022. 5.5% Senior Notes Senior Notes Due2022 [Member] Senior Notes 5.75%. 5.75% Senior Notes Senior Notes575 [Member] Fair Value Hierarchy and NAV Fair Value By Fair Value Hierarchy Level [Axis] Fair Value Hierarchy and NAV Fair Value Measurements Fair Value Hierarchy [Domain] Estimated fair value (Level 2) Fair Value Inputs Level2 [Member] Senior notes Notes Payable Fair Value Disclosure 5.75% Senior Notes Debt face amount Debt Instrument Face Amount Partners capital account units partial settlement. Schedule Of Stock By Class [Table] Schedule Of Stock By Class [Table] Series A Preferred Units Represents information pertaining to general partner units issued by the partnership. General Partner Units General Partner Units [Member] Class Of Stock [Line Items] Class Of Stock [Line Items] Rollforwards of the number of partner units Increase Decrease In Partners Capital Roll Forward Units, beginning balance (in shares) Partners Capital Account Units Units issued in connection with offering Partners Capital Account Units Sale Of Units Net units issued under SMLP LTIP (in shares) Partners Capital Account Units Unitbased Compensation Units issued under ATM program (in shares) Partners Capital Account Units Sold In Public Offering General Partner 2% capital contribution (in shares) Partners Capital Account Units Contributed Units, ending balance (in shares) DPPO partial settlement Partners Capital Account Units Partial Settlement Partners' capital. Partners' capital. Partners Capital [Table] Partners Capital [Table] Managing Member or General Partner Incentive Distribution Made To Managing Member Or General Partner [Axis] Incentive Distribution, Recipient Incentive Distribution Recipient [Domain] GP or IDR exchange. GP/IDR Exchange G P Or I D R Exchange [Member] Limited Partner Limited Partner [Member] Affiliate of Energy Capital Partners II, LLC. Affiliate of Energy Capital Partners II, LLC Affiliate Of Energy Capital Partners I I L L C [Member] Public offering. Public Offering Public Offering [Member] Registration Payment Arrangement by Arrangement Registration Payment Arrangement By Arrangement [Axis] Registration Payment Arrangement, Arrangement Registration Payment Arrangement Arrangement [Domain] Two thousand sixteen SRS. 2016 SRS Two Thousand Sixteen S R S [Member] Class of Stock Statement Class Of Stock [Axis] Class of Stock Class Of Stock [Domain] Series A Preferred Units Series A Preferred Stock [Member] Permian Holdco. Permian Holdco Permian Holdco [Member] Subsequent Event Type Subsequent Event Type [Axis] Subsequent Event Type Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Long-term Debt, Type Longterm Debt Type [Axis] Long-term Debt, Type Longterm Debt Type [Domain] Paid-in-kind Payment In Kind P I K Note [Member] Partners Capital [Line Items] Partners Capital [Line Items] Fair value Limited partner interest ownership percentage Limited Liability Company L L C Or Limited Partnership L P Members Or Limited Partners Ownership Interest IDR payments Incentive Distribution Distribution Per Year Proceeds from Issuance of common stock Proceeds From Issuance Of Common Stock Partners' capital account, public sale of units, remaining amount authorized. Aggregate offering price Partners Capital Account Public Saleof Units Remaining Amount Authorized Number of transactions under ATM Program. Transactions under ATM Program Number Of Transactions Under A T M Transactions Under A T M Program Aggregate gross proceeds Compensation paid to sales agents Payments To Acquire Limited Partnership Interests Preferred units issued Interest in partnership per unit Distribution Made To Limited Partner Distributions Paid Per Unit Repayment of outstanding revolving credit facility Distribution percentage of liquidation preference rate. Distribution percentage of liquidation preference rate description. Distribution rate Preferred Stock Dividend Rate Percentage Liquidation preference per unit Preferred Stock Liquidation Preference Distribution percentage of liquidation preference rate description Distribution Percentage Of Liquidation Preference Rate Description Distribution percentage of liquidation preference rate Distribution Percentage Of Liquidation Preference Rate Series A preferred per unit, price Shares Issued Price Per Share Percentage of subsidiary units. Percentage of undrawn commitment units. Distribution percentage of subsidiary unit Percentage Of Subsidiary Units Distribution percentage of liquidation preference rate of undrawn commitment units Percentage Of Undrawn Commitment Units Purchase of noncontrolling interest Payments To Minority Shareholders Distribution of all available cash, maximum period following end of quarter. Maximum period following end of quarter to distribute all available cash Distribution Of All Available Cash Maximum Period Following End Of Quarter Per-unit annual distributions to unitholders (in dollars per unit) Distribution Made To Limited Partner Distributions Declared Per Unit Cash paid to unit holders Distribution Made To Limited Partner Cash Distributions Declared Cash distribution date Distribution Made To Limited Partner Distribution Date Cash distribution date of record Distribution Made To Limited Partner Date Of Record Pro-rated issuance of preferred units. Pro-rated distribution of preferred units. Pro rated distribution of preferred units annual basis. Pro-rated issuance of preferred units Pro Rated Issuance Of Preferred Units Pro-rated distribution of preferred units Pro Rated Distribution Of Preferred Units Pro-rated distribution of preferred units Pro Rated Distribution Of Preferred Units Annual Basis Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Limited partner interest before subordinated units converted to common units.. Limited Partner Interest Before Subordinated Units Converted To Common Units Limited Partner Interest Before Subordinated Units Converted To Common Units [Member] Represents information pertaining to subordinated units issued by the partnership. Subordinated Units Subordinated Units [Member] Antidilutive Securities Antidilutive Securities Excluded From Computation Of Earnings Per Share By Antidilutive Securities [Axis] Antidilutive Securities, Name Antidilutive Securities Name [Domain] Phantom Units Phantom Share Units P S Us [Member] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Net (loss) income attributable to limited partners Weighted-average common units outstanding – basic Effect of nonvested phantom units Incremental Common Shares Attributable To Share Based Payment Arrangements Weighted-average common units outstanding – diluted Common unit – basic Common unit – diluted Nonvested anti-dilutive phantom units excluded from the calculation of diluted EPU Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Plan Name Plan Name [Axis] Plan Name Plan Name [Domain] Long-term incentive plan. SMLP LTIP Long Term Incentive Plan [Member] Award Type Award Type [Axis] Award Type Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Reserved for issuance (in shares) Share Based Compensation Arrangement By Share Based Payment Award Number Of Additional Shares Authorized Units remaining available Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Units Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Roll Forward Nonvested units(in shares) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number Units granted (in shares) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Unit vested (in shares) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Units forfeited (in shares) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period Nonvested units(in shares) Weighted-average grant date fair value Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value Roll Forward Nonvested, Weighted-average grant date fair value, beginning (in dollars per unit) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value Units granted, Weighted-average grant date fair value (in dollars per unit) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value Units vested, Weighted-average grant date fair value (in dollars per unit) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value Units forfeited, Weighted-average grant date fair value (in dollars per unit) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value Nonvested, Weighted-average grant date fair value, beginning (in dollars per unit) Vesting period Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 Intrinsic value of vested LTIP awards Sharebased Compensation Arrangement By Sharebased Payment Award Equity Instruments Other Than Options Aggregate Intrinsic Value Vested Unrecognized unit-based compensation Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Weighted-average remaining vesting period Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 General and administrative expense General And Administrative Expense [Member] SMLP LTIP unit-based compensation Schedule Of Related Party Transactions By Related Party [Table] Schedule Of Related Party Transactions By Related Party [Table] Related Party Transaction Related Party Transaction [Axis] Related Party Transaction Related Party Transaction [Domain] Compression services agreement. Compression Services Agreement Compression Services Agreement [Member] RELATED-PARTY TRANSACTIONS Related Party Transaction [Line Items] Shares sold (in shares) Sale Of Stock Number Of Shares Issued In Transaction Operation and maintenance expense Operating Expense [Member] Expenses from transactions with related party Related Party Transaction Expenses From Transactions With Related Party Sale price (in dollars per share) Sale Of Stock Price Per Share Loss Contingencies [Table] Loss Contingencies [Table] Office space. Office Space Office Space [Member] Equipment Equipment [Member] Business Interruption Loss Business Interruption Loss [Axis] Business Interruption Loss Business Interruption Loss [Domain] Business interruption. Business Interruption Business Interruption [Member] Property recoveries. Property Recoveries Property Recoveries [Member] Environmental Remediation Site Environmental Remediation Site [Axis] Environmental Remediation Site Environmental Remediation Site [Domain] Meadowlark Midstream gathering system. Meadowlark Midstream Gathering System Meadowlark Midstream Gathering System [Member] Principal Owner Loss Contingencies [Line Items] Loss Contingencies [Line Items] Operating leases, term of contract Lessee Operating Lease Term Of Contract Finance leases, term of contract Lessee Finance Lease Term Of Contract1 Lease operating lease number of renewal terms. Lessee, operating lease, existence of option to extend [true false] Lessee Operating Lease Existence Of Option To Extend Lessee, operating lease, option to extend Lessee Operating Lease Option To Extend Operating lease, number of renewal terms Lease Operating Lease Number Of Renewal Terms Lease agreements renewal periods Lessee Operating Lease Renewal Term Maximum amount of finance and operating lease obligations. Incremental borrowing rate. Lessee, operating lease, existence of residual value guarantee [true false] Lessee Operating Lease Existence Of Residual Value Guarantee Lessee, operating lease, residual value guarantee, Description Lessee Operating Lease Residual Value Guarantee Description Finance operating Lease obligations not exceed consolidated total assets Maximum Amount Of Finance And Operating Lease Obligations Lessee, operating lease, assumptions and judgments, whether contract is or contains lease Lessee Operating Lease Assumptions And Judgments Whether Contract Is Or Contains Lease Lessee, operating lease, assumptions and judgments, discount rate, description Lessee Operating Lease Assumptions And Judgments Discount Rate Description Percentage of operating lease incremental borrowing rate Incremental Borrowing Rate Public utilities electric power additional capacity expected from new plant. Project cost. Up front payment included in property, plant and equipment. Additional cost to increase transmission line capacity. Letter of credit initial term Letter of credit renew term. Electric power Public Utilities Electric Power Additional Capacity Expected From New Plant Cost of project Project Cost Up front payment included in property, plant and equipment Up Front Payment Included In Property Plant And Equipment Additional cost to increase transmission line capacity Additional Cost To Increase Transmission Line Capacity Letter of credit initial term Letter Of Credit Initial Term Irrevocable letter of credit payable Letter of credit renew term Letter Of Credit Renew Term Future minimum sublease payment Operating Leases Future Minimum Payments Due Future Minimum Sublease Rentals Finance and operating lease right of use asset. Lease liabilities current abstract. Finance and operating lease liability current. Lease liabilities noncurrent abstract. Finance and operating lease liability noncurrent. Finance Finance Lease Right Of Use Asset Total Finance And Operating Lease Right Of Use Asset Lease liabilities, current Lease Liabilities Current [Abstract] Operating Operating Lease Liability Current Finance Finance Lease Liability Current Total Finance And Operating Lease Liability Current Lease liabilities, noncurrent Lease Liabilities Noncurrent [Abstract] Operating Operating Lease Liability Noncurrent Finance Finance Lease Liability Noncurrent Total Finance And Operating Lease Liability Noncurrent Finance lease cost abstract Lease cost Lease Cost [Abstract] Finance lease cost: Finance Lease Costs [Abstract] Amortization of ROU assets (included in depreciation and amortization) Finance Lease Right Of Use Asset Amortization Interest on lease liabilities (included in interest expense) Finance Lease Interest Expense Operating lease cost (included in general and administrative expense) Operating Lease Cost Total lease cost Lease Cost Other information Income And Expenses Lessee [Abstract] Operating cash outflows from operating leases Operating Lease Payments Operating cash outflows from finance leases Finance Lease Interest Payment On Liability Financing cash outflows from finance leases Finance Lease Principal Payments ROU assets obtained in exchange for new operating lease liabilities Right Of Use Asset Obtained In Exchange For Operating Lease Liability ROU assets obtained in exchange for new finance lease liabilities Right Of Use Asset Obtained In Exchange For Finance Lease Liability Weighted-average remaining lease term (years) - operating leases Operating Lease Weighted Average Remaining Lease Term1 Weighted-average remaining lease term (years) - finance leases Finance Lease Weighted Average Remaining Lease Term1 Weighted-average discount rate - operating leases Operating Lease Weighted Average Discount Rate Percent Weighted-average discount rate - finance leases Finance Lease Weighted Average Discount Rate Percent Lease expense Operating Lease Expense Lessee operating lease liability payments due year six. Lessee operating lease liability payments due after year six. Finance lease liability payments due year six. Finance lease liability payments due after year six. Operating lease, Future minimum lease payments, 2020 Lessee Operating Lease Liability Payments Due Next Twelve Months Operating lease, Future minimum lease payments, 2021 Lessee Operating Lease Liability Payments Due Year Two Operating lease, Future minimum lease payments, 2022 Lessee Operating Lease Liability Payments Due Year Three Operating lease, Future minimum lease payments, 2023 Lessee Operating Lease Liability Payments Due Year Four Operating lease, Future minimum lease payments, 2024 Lessee Operating Lease Liability Payments Due Year Five Operating lease, Future minimum lease payments, 2025 Lessee Operating Lease Liability Payments Due Year Six Operating lease, Future minimum lease payments, Thereafter Lessee Operating Lease Liability Payments Due After Year Six Operating lease, Total future minimum lease payments Lessee Operating Lease Liability Payments Due Finance lease, Future minimum lease payments, 2020 Finance Lease Liability Payments Due Next Twelve Months Finance lease, Future minimum lease payments, 2021 Finance Lease Liability Payments Due Year Two Finance lease, Future minimum lease payments, 2022 Finance Lease Liability Payments Due Year Three Finance lease, Future minimum lease payments, 2023 Finance Lease Liability Payments Due Year Four Finance lease, Future minimum lease payments, 2024 Finance Lease Liability Payments Due Year Five Finance lease, Future minimum lease payments, 2025 Finance Lease Liability Payments Due Year Six Finance lease, Future minimum lease payments, Thereafter Finance Lease Liability Payments Due After Year Six Finance lease, Total future minimum lease payments Finance Lease Liability Payments Due 2019 Operating Leases Future Minimum Payments Due Current 2020 Operating Leases Future Minimum Payments Due In Two Years 2021 Operating Leases Future Minimum Payments Due In Three Years 2022 Operating Leases Future Minimum Payments Due In Four Years 2023 Operating Leases Future Minimum Payments Due In Five Years Thereafter Operating Leases Future Minimum Payments Due Thereafter Total future minimum lease payments Operating Leases Future Minimum Payments Due 2019 Capital Leases Future Minimum Payments Due Current 2020 Capital Leases Future Minimum Payments Due In Two Years 2021 Capital Leases Future Minimum Payments Due In Three Years Total finance lease obligations Capital Leases Future Minimum Payments Due Less: Amounts representing interest Capital Leases Future Minimum Payments Interest Included In Payments Net present value of finance lease obligations Capital Leases Future Minimum Payments Present Value Of Net Minimum Payments Less: Amount representing current portion (included in Other current liabilities) Capital Lease Obligations Current Finance lease obligations, less current portion (included in Other noncurrent liabilities) Capital Lease Obligations Noncurrent Loss contingency, pollution liability insurance policy, coverage. Loss contingency, property and business interruption insurance policy, coverage. Coverage from pollution liability insurance policy Loss Contingency Pollution Liability Insurance Policy Coverage Coverage from property and business interruption insurance policy Loss Contingency Property And Business Interruption Insurance Policy Coverage Recoveries recognized Gain On Business Interruption Insurance Recovery Accrual for Environmental Loss Contingencies [Roll Forward] Accrual For Environmental Loss Contingencies Roll Forward Accrued environmental remediation, beginning balance Accrual For Environmental Loss Contingencies Payments made Accrual For Environmental Loss Contingencies Payments1 Additional accruals Accrual For Environmental Loss Contingencies Period Increase Decrease Accrued environmental remediation, ending balance Schedule Of Business Acquisitions By Acquisition [Table] Schedule Of Business Acquisitions By Acquisition [Table] Disposal Group Name Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Axis] Disposal Group Name Disposal Groups Including Discontinued Operations Name [Domain] Disposal Group Classification Disposal Group Classification [Axis] Disposal Group Classification Disposal Group Classification [Domain] Disposal, not discontinued operations Disposal Group Disposed Of By Sale Not Discontinued Operations [Member] Collaborative Arrangement and Arrangement Other than Collaborative Type Of Arrangement [Axis] Collaborative Arrangement and Arrangement Other than Collaborative Arrangements And Nonarrangement Transactions [Member] Purchase and sale agreement Purchase and Sale Agreement Purchase And Sale Agreement [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Number of purchase and sale agreement. Tioga Midstream, LLC. Tioga Midstream, LLC Tioga Midstream L L C [Member] Number of purchase and sale agreements Number Of Purchase And Sale Agreement Gain on sale of business Gain Loss On Sale Of Business Transactions under common control, working capital adjustment. Working capital adjustment Transactions Under Common Control Working Capital Adjustment Business combination remaining Consideration to be paid percentage. Minimum remaining consideration to be paid percentage Business Combination Minimum Remaining Consideration To Be Paid Percentage Transactions under common control, contingent consideration liability, discount rate. Estimated future payment obligation Business Combination Contingent Consideration Arrangements Range Of Outcomes Value High Deferred purchase price obligation Business Combination Contingent Consideration Liability Discount rate Transactions Under Common Control Contingent Consideration Liability Discount Rate Restructuring Plan Restructuring Plan [Axis] Restructuring Plan Restructuring Plan [Domain] EmployeeRelatedCostsMember Employee Related Costs Employee Related Costs [Member] Consultants Member. Consultants Consultants [Member] Restructuring costs Restructuring Costs Restructuring and related cost, expected cost Restructuring And Related Cost Expected Cost1 Severance costs Severance Costs1 Employee related cost included in current liabilities Employee Related Liabilities Current Consultant related liabilities current. Consultant related liabilities current Consultant Related Liabilities Current Unrestricted Subsidiaries [Member] Unrestricted Subsidiaries Unrestricted Subsidiaries [Member] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] SMLP Parent Company [Member] Co-Issuers Subsidiary Issuer [Member] Non-Guarantor Subsidiaries Non Guarantor Subsidiaries [Member] Consolidation Adjustments Consolidation Eliminations [Member] Condensed Balance Sheet Statements Captions [Line Items] Condensed Balance Sheet Statements Captions [Line Items] Due from affiliate Due From Affiliate Current Investment in subsidiaries Investments In Affiliates Subsidiaries Associates And Joint Ventures Total partners' capital Condensed Income Statement [Table] Condensed Income Statement [Table] Condensed Income Statements Captions [Line Items] Condensed Income Statements Captions [Line Items] Other income Equity in earnings of consolidated subsidiaries Income Loss From Subsidiaries Net Of Tax Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statements Captions [Line Items] Condensed Cash Flow Statements Captions [Line Items] Net cash provided by (used in) operating activities Advances to affiliates Payments For Proceeds From Advances To Affiliates Advances from affiliates Payments For Proceeds From Advances From Affiliates Schedule Of Limited Partners Capital Account By Class [Table] Schedule Of Limited Partners Capital Account By Class [Table] Limited Partners' Capital Account [Line Items] Limited Partners Capital Account [Line Items] Net (loss) income attributable to SMLP Less net income and IDRs attributable to General Partner Net Income Loss Allocated To General Partners