3.10.0.1 html 511 312 1 true 112 0 false 5 false false R1.htm 0001000 - Document - Document and Entity Information Sheet http://www.semgroupcorp.com/role/DocumentAndEntityInformation Document and Entity Information Cover 1 false false R2.htm 1001000 - Statement - Condensed Consolidated Balance Sheets Sheet http://www.semgroupcorp.com/role/CondensedConsolidatedBalanceSheets Condensed Consolidated Balance Sheets Statements 2 false false R3.htm 1001501 - Statement - Condensed Consolidated Balance Sheets (Parenthetical) Sheet http://www.semgroupcorp.com/role/CondensedConsolidatedBalanceSheetsParenthetical Condensed Consolidated Balance Sheets (Parenthetical) Statements 3 false false R4.htm 1002000 - Statement - Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) Sheet http://www.semgroupcorp.com/role/CondensedConsolidatedStatementsOfOperationsAndComprehensiveIncomeUnaudited Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) Statements 4 false false R5.htm 1003000 - Statement - Condensed Consolidated Statements of Changes in Owners' Equity Statement Sheet http://www.semgroupcorp.com/role/CondensedConsolidatedStatementsOfChangesInOwnersEquityStatement Condensed Consolidated Statements of Changes in Owners' Equity Statement Statements 5 false false R6.htm 1004000 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited) Sheet http://www.semgroupcorp.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited Condensed Consolidated Statements of Cash Flows (Unaudited) Statements 6 false false R7.htm 2101100 - Disclosure - Overview Sheet http://www.semgroupcorp.com/role/Overview Overview Notes 7 false false R8.htm 2103100 - Disclosure - Disposal of long-lived assets Sheet http://www.semgroupcorp.com/role/DisposalOfLongLivedAssets Disposal of long-lived assets Notes 8 false false R9.htm 2105100 - Disclosure - Equity Method Investments Sheet http://www.semgroupcorp.com/role/EquityMethodInvestments Equity Method Investments Notes 9 false false R10.htm 2106100 - Disclosure - Financial Instruments Sheet http://www.semgroupcorp.com/role/FinancialInstruments Financial Instruments Notes 10 false false R11.htm 2107100 - Disclosure - Income Taxes Sheet http://www.semgroupcorp.com/role/IncomeTaxes Income Taxes Notes 11 false false R12.htm 2108100 - Disclosure - Long-Term Debt Sheet http://www.semgroupcorp.com/role/LongTermDebt Long-Term Debt Notes 12 false false R13.htm 2109100 - Disclosure - Commitments and Contingencies Sheet http://www.semgroupcorp.com/role/CommitmentsAndContingencies Commitments and Contingencies Notes 13 false false R14.htm 2110100 - Disclosure - Equity Sheet http://www.semgroupcorp.com/role/Equity Equity Notes 14 false false R15.htm 2111100 - Disclosure - Preferred Stock Sheet http://www.semgroupcorp.com/role/PreferredStock Preferred Stock Notes 15 false false R16.htm 2112100 - Disclosure - Accumulated Other Comprehensive Income(Notes) Notes http://www.semgroupcorp.com/role/AccumulatedOtherComprehensiveIncomenotes Accumulated Other Comprehensive Income(Notes) Notes 16 false false R17.htm 2113100 - Disclosure - Revenue Sheet http://www.semgroupcorp.com/role/Revenue Revenue Notes 17 false false R18.htm 2114100 - Disclosure - Segments Sheet http://www.semgroupcorp.com/role/Segments Segments Notes 18 false false R19.htm 2115100 - Disclosure - Earnings Per Share Sheet http://www.semgroupcorp.com/role/EarningsPerShare Earnings Per Share Notes 19 false false R20.htm 2116100 - Disclosure - Supplemental Cash Flow Information Sheet http://www.semgroupcorp.com/role/SupplementalCashFlowInformation Supplemental Cash Flow Information Notes 20 false false R21.htm 2117100 - Disclosure - Related Party Transactions Sheet http://www.semgroupcorp.com/role/RelatedPartyTransactions Related Party Transactions Notes 21 false false R22.htm 2118100 - Disclosure - Condensed Consolidating Guarantor Financial Statements (Notes) Notes http://www.semgroupcorp.com/role/CondensedConsolidatingGuarantorFinancialStatementsNotes Condensed Consolidating Guarantor Financial Statements (Notes) Notes 22 false false R23.htm 2201201 - Disclosure - Overview (Policies) Sheet http://www.semgroupcorp.com/role/OverviewPolicies Overview (Policies) Policies 23 false false R24.htm 2206201 - Disclosure - Financial Instruments (Policies) Sheet http://www.semgroupcorp.com/role/FinancialInstrumentsPolicies Financial Instruments (Policies) Policies 24 false false R25.htm 2301302 - Disclosure - Overview (Tables) Sheet http://www.semgroupcorp.com/role/OverviewTables Overview (Tables) Tables http://www.semgroupcorp.com/role/Overview 25 false false R26.htm 2305301 - Disclosure - Equity Method Investments (Tables) Sheet http://www.semgroupcorp.com/role/EquityMethodInvestmentsTables Equity Method Investments (Tables) Tables http://www.semgroupcorp.com/role/EquityMethodInvestments 26 false false R27.htm 2306302 - Disclosure - Financial Instruments (Tables) Sheet http://www.semgroupcorp.com/role/FinancialInstrumentsTables Financial Instruments (Tables) Tables http://www.semgroupcorp.com/role/FinancialInstruments 27 false false R28.htm 2308301 - Disclosure - Long-Term Debt (Tables) Sheet http://www.semgroupcorp.com/role/LongTermDebtTables Long-Term Debt (Tables) Tables http://www.semgroupcorp.com/role/LongTermDebt 28 false false R29.htm 2309301 - Disclosure - Commitments and Contingencies (Tables) Sheet http://www.semgroupcorp.com/role/CommitmentsAndContingenciesTables Commitments and Contingencies (Tables) Tables http://www.semgroupcorp.com/role/CommitmentsAndContingencies 29 false false R30.htm 2310301 - Disclosure - Equity (Tables) Sheet http://www.semgroupcorp.com/role/EquityTables Equity (Tables) Tables http://www.semgroupcorp.com/role/EquityMethodInvestments 30 false false R31.htm 2312301 - Disclosure - Accumulated Other Comprehensive Income (Tables) Sheet http://www.semgroupcorp.com/role/AccumulatedOtherComprehensiveIncomeTables Accumulated Other Comprehensive Income (Tables) Tables http://www.semgroupcorp.com/role/AccumulatedOtherComprehensiveIncomenotes 31 false false R32.htm 2313301 - Disclosure - Revenue (Tables) Sheet http://www.semgroupcorp.com/role/RevenueTables Revenue (Tables) Tables http://www.semgroupcorp.com/role/Revenue 32 false false R33.htm 2314301 - Disclosure - Segments (Tables) Sheet http://www.semgroupcorp.com/role/SegmentsTables Segments (Tables) Tables http://www.semgroupcorp.com/role/Segments 33 false false R34.htm 2315301 - Disclosure - Earnings Per Share (Tables) Sheet http://www.semgroupcorp.com/role/EarningsPerShareTables Earnings Per Share (Tables) Tables http://www.semgroupcorp.com/role/EarningsPerShare 34 false false R35.htm 2316301 - Disclosure - Supplemental Cash Flow Information (Tables) Sheet http://www.semgroupcorp.com/role/SupplementalCashFlowInformationTables Supplemental Cash Flow Information (Tables) Tables http://www.semgroupcorp.com/role/SupplementalCashFlowInformation 35 false false R36.htm 2317301 - Disclosure - Related Party Transactions (Tables) Sheet http://www.semgroupcorp.com/role/RelatedPartyTransactionsTables Related Party Transactions (Tables) Tables http://www.semgroupcorp.com/role/RelatedPartyTransactions 36 false false R37.htm 2318301 - Disclosure - Condensed Consolidating Guarantor Financial Statements (Tables) Sheet http://www.semgroupcorp.com/role/CondensedConsolidatingGuarantorFinancialStatementsTables Condensed Consolidating Guarantor Financial Statements (Tables) Tables http://www.semgroupcorp.com/role/CondensedConsolidatingGuarantorFinancialStatementsNotes 37 false false R38.htm 2401403 - Disclosure - Overview (Details 1) Sheet http://www.semgroupcorp.com/role/OverviewDetails1 Overview (Details 1) Details http://www.semgroupcorp.com/role/OverviewTables 38 false false R39.htm 2401404 - Disclosure - Overview (Details Textual) Sheet http://www.semgroupcorp.com/role/OverviewDetailsTextual Overview (Details Textual) Details http://www.semgroupcorp.com/role/OverviewTables 39 false false R40.htm 2403402 - Disclosure - Disposal of long-lived assets (Details) Sheet http://www.semgroupcorp.com/role/DisposalOfLongLivedAssetsDetails Disposal of long-lived assets (Details) Details http://www.semgroupcorp.com/role/DisposalOfLongLivedAssets 40 false false R41.htm 2405402 - Disclosure - Equity Method Investments - Investment balances (Details) Sheet http://www.semgroupcorp.com/role/EquityMethodInvestmentsInvestmentBalancesDetails Equity Method Investments - Investment balances (Details) Details 41 false false R42.htm 2405403 - Disclosure - Equity Method Investments - Equity earnings, by investment (Details) Sheet http://www.semgroupcorp.com/role/EquityMethodInvestmentsEquityEarningsByInvestmentDetails Equity Method Investments - Equity earnings, by investment (Details) Details 42 false false R43.htm 2405404 - Disclosure - Equity Method Investments - Distributions received, by investment (Details) Sheet http://www.semgroupcorp.com/role/EquityMethodInvestmentsDistributionsReceivedByInvestmentDetails Equity Method Investments - Distributions received, by investment (Details) Details 43 false false R44.htm 2405405 - Disclosure - Equity Method Investments - Summarized financial information - White Cliffs (Details) Sheet http://www.semgroupcorp.com/role/EquityMethodInvestmentsSummarizedFinancialInformationWhiteCliffsDetails Equity Method Investments - Summarized financial information - White Cliffs (Details) Details 44 false false R45.htm 2405406 - Disclosure - Equity Method Investments (Details Textual) Sheet http://www.semgroupcorp.com/role/EquityMethodInvestmentsDetailsTextual Equity Method Investments (Details Textual) Details http://www.semgroupcorp.com/role/EquityMethodInvestmentsTables 45 false false R46.htm 2406403 - Disclosure - Financial Instruments - Fair value of financial assets and liabilties (Details) Sheet http://www.semgroupcorp.com/role/FinancialInstrumentsFairValueOfFinancialAssetsAndLiabiltiesDetails Financial Instruments - Fair value of financial assets and liabilties (Details) Details 46 false false R47.htm 2406404 - Disclosure - Financial Instruments Financial Instruments - Level 3 Changes in Fair Value (Details) Sheet http://www.semgroupcorp.com/role/FinancialInstrumentsFinancialInstrumentsLevel3ChangesInFairValueDetails Financial Instruments Financial Instruments - Level 3 Changes in Fair Value (Details) Details 47 false false R48.htm 2406405 - Disclosure - Financial Instruments - Notional amounts (Details) Sheet http://www.semgroupcorp.com/role/FinancialInstrumentsNotionalAmountsDetails Financial Instruments - Notional amounts (Details) Details 48 false false R49.htm 2406406 - Disclosure - Financial Instruments - Fair value of commodity derivative assets and liabilities (Details) Sheet http://www.semgroupcorp.com/role/FinancialInstrumentsFairValueOfCommodityDerivativeAssetsAndLiabilitiesDetails Financial Instruments - Fair value of commodity derivative assets and liabilities (Details) Details 49 false false R50.htm 2406407 - Disclosure - Financial Instruments - Realized and unrealized gains and losses (Details) Sheet http://www.semgroupcorp.com/role/FinancialInstrumentsRealizedAndUnrealizedGainsAndLossesDetails Financial Instruments - Realized and unrealized gains and losses (Details) Details 50 false false R51.htm 2406408 - Disclosure - Financial Instruments (Details Textual) Sheet http://www.semgroupcorp.com/role/FinancialInstrumentsDetailsTextual Financial Instruments (Details Textual) Details http://www.semgroupcorp.com/role/FinancialInstrumentsTables 51 false false R52.htm 2407401 - Disclosure - Income Taxes (Details Textual) Sheet http://www.semgroupcorp.com/role/IncomeTaxesDetailsTextual Income Taxes (Details Textual) Details http://www.semgroupcorp.com/role/IncomeTaxes 52 false false R53.htm 2408402 - Disclosure - Long-Term Debt (Details) Sheet http://www.semgroupcorp.com/role/LongTermDebtDetails Long-Term Debt (Details) Details http://www.semgroupcorp.com/role/LongTermDebtTables 53 false false R54.htm 2408403 - Disclosure - Long-Term Debt Letters of Credit (Details) Sheet http://www.semgroupcorp.com/role/LongTermDebtLettersOfCreditDetails Long-Term Debt Letters of Credit (Details) Details 54 false false R55.htm 2408404 - Disclosure - Long-Term Debt (Details Textual) Sheet http://www.semgroupcorp.com/role/LongTermDebtDetailsTextual Long-Term Debt (Details Textual) Details http://www.semgroupcorp.com/role/LongTermDebtTables 55 false false R56.htm 2409402 - Disclosure - Commitments and Contingencies - Purchase and sales commitments (Details) Sheet http://www.semgroupcorp.com/role/CommitmentsAndContingenciesPurchaseAndSalesCommitmentsDetails Commitments and Contingencies - Purchase and sales commitments (Details) Details 56 false false R57.htm 2409403 - Disclosure - Commitments and Contingencies - Take or Pay (Details) Sheet http://www.semgroupcorp.com/role/CommitmentsAndContingenciesTakeOrPayDetails Commitments and Contingencies - Take or Pay (Details) Details 57 false false R58.htm 2409404 - Disclosure - Commitments and Contingencies - Take or Pay 2 (Details) Sheet http://www.semgroupcorp.com/role/CommitmentsAndContingenciesTakeOrPay2Details Commitments and Contingencies - Take or Pay 2 (Details) Details 58 false false R59.htm 2409405 - Disclosure - Commitments and Contingencies (Details Textual) Sheet http://www.semgroupcorp.com/role/CommitmentsAndContingenciesDetailsTextual Commitments and Contingencies (Details Textual) Details http://www.semgroupcorp.com/role/CommitmentsAndContingenciesTables 59 false false R60.htm 2410402 - Disclosure - Equity - Dividends (Details) Sheet http://www.semgroupcorp.com/role/EquityDividendsDetails Equity - Dividends (Details) Details 60 false false R61.htm 2410403 - Disclosure - Equity (Details Textual) Sheet http://www.semgroupcorp.com/role/EquityDetailsTextual Equity (Details Textual) Details http://www.semgroupcorp.com/role/EquityMethodInvestmentsTables 61 false false R62.htm 2411401 - Disclosure - Preferred Stock (Details Textual) Sheet http://www.semgroupcorp.com/role/PreferredStockDetailsTextual Preferred Stock (Details Textual) Details http://www.semgroupcorp.com/role/PreferredStock 62 false false R63.htm 2412402 - Disclosure - Accumulated Other Comprehensive Income (Details) Sheet http://www.semgroupcorp.com/role/AccumulatedOtherComprehensiveIncomeDetails Accumulated Other Comprehensive Income (Details) Details http://www.semgroupcorp.com/role/AccumulatedOtherComprehensiveIncomeTables 63 false false R64.htm 2413402 - Disclosure - Revenue (Details) Sheet http://www.semgroupcorp.com/role/RevenueDetails Revenue (Details) Details http://www.semgroupcorp.com/role/RevenueTables 64 false false R65.htm 2413403 - Disclosure - Revenue (Details 2) Sheet http://www.semgroupcorp.com/role/RevenueDetails2 Revenue (Details 2) Details http://www.semgroupcorp.com/role/RevenueTables 65 false false R66.htm 2413404 - Disclosure - Revenue (Details 3) Sheet http://www.semgroupcorp.com/role/RevenueDetails3 Revenue (Details 3) Details http://www.semgroupcorp.com/role/RevenueTables 66 false false R67.htm 2413405 - Disclosure - Revenue (Details Textual) Sheet http://www.semgroupcorp.com/role/RevenueDetailsTextual Revenue (Details Textual) Details http://www.semgroupcorp.com/role/RevenueTables 67 false false R68.htm 2414402 - Disclosure - Segments (Details) Sheet http://www.semgroupcorp.com/role/SegmentsDetails Segments (Details) Details http://www.semgroupcorp.com/role/SegmentsTables 68 false false R69.htm 2415402 - Disclosure - Earnings Per Share - Basic (Details) Sheet http://www.semgroupcorp.com/role/EarningsPerShareBasicDetails Earnings Per Share - Basic (Details) Details 69 false false R70.htm 2415403 - Disclosure - Earnings Per Share - Diluted (Details) Sheet http://www.semgroupcorp.com/role/EarningsPerShareDilutedDetails Earnings Per Share - Diluted (Details) Details 70 false false R71.htm 2416402 - Disclosure - Supplemental Cash Flow Information - Operating assets and liabilities (Details) Sheet http://www.semgroupcorp.com/role/SupplementalCashFlowInformationOperatingAssetsAndLiabilitiesDetails Supplemental Cash Flow Information - Operating assets and liabilities (Details) Details 71 false false R72.htm 2416403 - Disclosure - Supplemental Cash Flow Information (Details Textual) Sheet http://www.semgroupcorp.com/role/SupplementalCashFlowInformationDetailsTextual Supplemental Cash Flow Information (Details Textual) Details http://www.semgroupcorp.com/role/SupplementalCashFlowInformationTables 72 false false R73.htm 2417402 - Disclosure - Related Party Transactions (Details) Sheet http://www.semgroupcorp.com/role/RelatedPartyTransactionsDetails Related Party Transactions (Details) Details http://www.semgroupcorp.com/role/RelatedPartyTransactionsTables 73 false false R74.htm 2418402 - Disclosure - Condensed Consolidating Guarantor Financial Statements - Balance Sheets (Details) Sheet http://www.semgroupcorp.com/role/CondensedConsolidatingGuarantorFinancialStatementsBalanceSheetsDetails Condensed Consolidating Guarantor Financial Statements - Balance Sheets (Details) Details 74 false false R75.htm 2418403 - Disclosure - Condensed Consolidating Guarantor Financial Statements - Statements of Operations (Details) Sheet http://www.semgroupcorp.com/role/CondensedConsolidatingGuarantorFinancialStatementsStatementsOfOperationsDetails Condensed Consolidating Guarantor Financial Statements - Statements of Operations (Details) Details 75 false false R76.htm 2418404 - Disclosure - Condensed Consolidating Guarantor Financial Statements - Cash Flow Statements (Details) Sheet http://www.semgroupcorp.com/role/CondensedConsolidatingGuarantorFinancialStatementsCashFlowStatementsDetails Condensed Consolidating Guarantor Financial Statements - Cash Flow Statements (Details) Details 76 false false All Reports Book All Reports semg9301810-q.htm a93018exhibit101.htm a93018exhibit311.htm a93018exhibit312.htm a93018exhibit321.htm a93018exhibit322.htm semg-20180930.xsd semg-20180930_cal.xml semg-20180930_def.xml semg-20180930_lab.xml semg-20180930_pre.xml http://xbrl.sec.gov/invest/2013-01-31 http://fasb.org/us-gaap/2018-01-31 http://xbrl.sec.gov/dei/2018-01-31 http://fasb.org/srt/2018-01-31 true true