1.0.0.3 false CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands false 1 $ false false u000 Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 u001 Standard http://www.xbrl.org/2003/instance shares xbrli 0 u002 Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 false 2 $ false false u000 Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 u001 Standard http://www.xbrl.org/2003/instance shares xbrli 0 u002 Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 false 3 $ false false u000 Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 u001 Standard http://www.xbrl.org/2003/instance shares xbrli 0 u002 Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 3 Operating activities 1 us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 4 Net income 2 us-gaap_ProfitLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 434704000 434704 false false 2 true true 626057000 626057 false false 3 true true 408163000 408163 false false No definition available. No authoritative reference available. false 5 Depreciation and amortization 2 us-gaap_DepreciationDepletionAndAmortization us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 164136000 164136 false false 2 false true 124765000 124765 false false 3 false true 113704000 113704 false false No definition available. No authoritative reference available. false 6 Allowance for equity funds used during construction 2 oks_AllowancesForEquityFundsUsedDuringConstruction oks false credit duration monetary The cost of equity related to financing the construction of regulated assets. false false false false false false false false false 1 false true -26868000 -26868 false false 2 false true -50906000 -50906 false false 3 false true -12538000 -12538 false false The cost of equity related to financing the construction of regulated assets. No authoritative reference available. false 7 Gain on sale of assets 2 us-gaap_GainLossOnSaleOfPropertyPlantEquipment us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -2668000 -2668 false false 2 false true -713000 -713 false false 3 false true -1950000 -1950 false false No definition available. No authoritative reference available. false 8 Deferred income taxes 2 us-gaap_DeferredIncomeTaxExpenseBenefit us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 11707000 11707 false false 2 false true 5015000 5015 false false 3 false true 4567000 4567 false false No definition available. No authoritative reference available. false 9 Equity earnings from investments 2 us-gaap_IncomeLossFromEquityMethodInvestments us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -72722000 -72722 false false 2 false true -101432000 -101432 false false 3 false true -89908000 -89908 false false No definition available. No authoritative reference available. false 10 Distributions received from unconsolidated affiliates 2 us-gaap_EquityMethodInvestmentDividendsOrDistributions us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 75377000 75377 false false 2 false true 93261000 93261 false false 3 false true 103785000 103785 false false No definition available. No authoritative reference available. false 11 Changes in assets and liabilities, net of effect of acquisitions: 2 us-gaap_IncreaseDecreaseInOperatingCapitalAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 12 Accounts receivable 3 us-gaap_IncreaseDecreaseInReceivables us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -308703000 -308703 false false 2 false true 256137000 256137 false false 3 false true -268963000 -268963 false false No definition available. No authoritative reference available. false 13 Affiliate receivables 3 us-gaap_IncreaseDecreaseInDueFromAffiliatesCurrent us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -6621000 -6621 false false 2 false true 26703000 26703 false false 3 false true 36093000 36093 false false No definition available. No authoritative reference available. false 14 Gas and natural gas liquids in storage 3 us-gaap_IncreaseDecreaseInInventories us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -26969000 -26969 false false 2 false true 16003000 16003 false false 3 false true -47973000 -47973 false false No definition available. No authoritative reference available. false 15 Derivative financial instruments 3 oks_DerivativeFinancialInstruments oks false credit duration monetary Change in carrying amount of the asset arising from derivative instruments and hedging activities, which are expected to be... false false false false false false false false false 1 false true -4349000 -4349 false false 2 false true -2538000 -2538 false false 3 false true 2154000 2154 false false Change in carrying amount of the asset arising from derivative instruments and hedging activities, which are expected to be converted into cash or otherwise disposed of within a year or the normal operating cycle, if longer. No authoritative reference available. false 16 Accounts payable 3 us-gaap_IncreaseDecreaseInAccountsPayableTrade us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 233921000 233921 false false 2 false true -273475000 -273475 false false 3 false true 368452000 368452 false false No definition available. No authoritative reference available. false 17 Affiliate payables 3 us-gaap_IncreaseDecreaseInDueToAffiliatesCurrent us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -1467000 -1467 false false 2 false true 5035000 5035 false false 3 false true -7439000 -7439 false false No definition available. No authoritative reference available. false 18 Commodity imbalances, net 3 oks_CommodityExchangesAndImbalancesNet oks false debit duration monetary The net change during the reporting period in the asset (liability) created by natural gas imbalances and NGL exchange... false false false false false false false false false 1 false true 68432000 68432 false false 2 false true -33979000 -33979 false false 3 false true 41997000 41997 false false The net change during the reporting period in the asset (liability) created by natural gas imbalances and NGL exchange agreements that are valued at market or their contractually stipulated rate. No authoritative reference available. false 19 Accrued interest 3 us-gaap_IncreaseDecreaseInInterestPayableNet us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 6600000 6600 false false 2 false true 5669000 5669 false false 3 false true 9069000 9069 false false No definition available. No authoritative reference available. false 20 Other assets and liabilities 3 us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 17929000 17929 false false 2 false true -39184000 -39184 false false 3 false true 42321000 42321 false false No definition available. No authoritative reference available. false 21 Cash provided by operating activities 3 us-gaap_NetCashProvidedByUsedInOperatingActivities us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 562439000 562439 false false 2 false true 656418000 656418 false false 3 false true 701534000 701534 false false No definition available. No authoritative reference available. true 22 Investing activities 1 us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 23 Changes in investments in unconsolidated affiliates 2 oks_ChangesInInvestmentsInUnconsolidatedAffiliates oks false debit duration monetary The net cash inflow (outflow) associated with distributions received from unconsolidated affiliates that constitute a return... false false false false false false false false false 1 false true -12031000 -12031 false false 2 false true 3963000 3963 false false 3 false true -3668000 -3668 false false The net cash inflow (outflow) associated with distributions received from unconsolidated affiliates that constitute a return of investment net of investments in or advances to unconsolidated affiliates. Unconsolidated affiliates are investments in joint ventures and entities in which the entity has an equity ownership interest. No authoritative reference available. false 24 Acquisitions 2 us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true 2450000 2450 false false 3 false true -299560000 -299560 false false No definition available. No authoritative reference available. false 25 Capital expenditures (less allowance for equity funds used during construction) 2 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -615691000 -615691 false false 2 false true -1253853000 -1253853 false false 3 false true -709858000 -709858 false false No definition available. No authoritative reference available. false 26 Proceeds from sale of assets and other 2 us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 9572000 9572 false false 2 false true 990000 990 false false 3 false true 3980000 3980 false false No definition available. No authoritative reference available. false 27 Cash used in investing activities 2 us-gaap_NetCashProvidedByUsedInInvestingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -618150000 -618150 false false 2 false true -1246450000 -1246450 false false 3 false true -1009106000 -1009106 false false No definition available. No authoritative reference available. true 28 Financing activities 1 us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 29 Cash distributions: General and limited partners 2 oks_GeneralAndLimitedPartners oks false credit duration monetary The cash outflow from the entity's earnings to the unitholders and general partner. false false false false false false false false false 1 false true -500253000 -500253 false false 2 false true -453021000 -453021 false false 3 false true -384646000 -384646 false false The cash outflow from the entity's earnings to the unitholders and general partner. No authoritative reference available. false 30 Cash distributions: Noncontrolling interests 2 us-gaap_PaymentsOfDividendsMinorityInterest us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -686000 -686 false false 2 false true -302000 -302 false false 3 false true -220000 -220 false false No definition available. No authoritative reference available. false 31 Borrowing (payment) of notes payable, net 2 us-gaap_ProceedsFromShortTermDebtMaturingInThreeMonthsOrLess us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 523000000 523000 false false 2 false true -100000000 -100000 false false 3 false true 94000000 94000 false false No definition available. No authoritative reference available. false 32 Borrowing (payment) of notes payable with maturities over 90 days 2 us-gaap_RepaymentsOfShortTermDebtMaturingInMoreThanThreeMonths us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -870000000 -870000 false false 2 false true 870000000 870000 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 33 Issuance of long-term debt, net of discounts 2 us-gaap_ProceedsFromIssuanceOfLongTermDebt us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 498325000 498325 false false 2 false true 0 0 false false 3 false true 598146000 598146 false false No definition available. No authoritative reference available. false 34 Long-term debt financing costs 2 us-gaap_PaymentsOfFinancingCosts us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -4000000 -4000 false false 2 false true 0 0 false false 3 false true -5805000 -5805 false false No definition available. No authoritative reference available. false 35 Repayment of long-term debt 2 us-gaap_RepaymentsOfLongTermDebt us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -11931000 -11931 false false 2 false true -11929000 -11929 false false 3 false true -11931000 -11931 false false No definition available. No authoritative reference available. false 36 Issuance of common units, net of discounts 2 us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 241642000 241642 false false 2 false true 450198000 450198 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 37 Contribution from general partner 2 us-gaap_ProceedsFromOtherEquity us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 5130000 5130 false false 2 false true 9508000 9508 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 38 Other financing activities 2 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true 0 0 false false 3 false true 139000 139 false false No definition available. No authoritative reference available. false 39 Cash provided by (used in) financing activities 2 us-gaap_NetCashProvidedByUsedInFinancingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -118773000 -118773 false false 2 false true 764454000 764454 false false 3 false true 289683000 289683 false false No definition available. No authoritative reference available. true 40 Change in cash and cash equivalents 1 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true -174484000 -174484 false false 2 false true 174422000 174422 false false 3 false true -17889000 -17889 false false No definition available. No authoritative reference available. true 41 Cash and cash equivalents at beginning of period 1 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false true false false 1 false true 177635000 177635 false false 2 false true 3213000 3213 false false 3 false true 21102000 21102 false false No definition available. No authoritative reference available. false 42 Cash and cash equivalents at end of period 1 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false false true false 1 false true 3151000 3151 false false 2 false true 177635000 177635 false false 3 false true 3213000 3213 false false No definition available. No authoritative reference available. false 43 Supplemental cash flow information: 1 us-gaap_SupplementalCashFlowInformationAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 44 Cash paid for interest, net of amounts capitalized 2 us-gaap_InterestPaid us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 201773000 201773 false false 2 false true 148417000 148417 false false 3 false true 138606000 138606 false false No definition available. No authoritative reference available. false 45 Cash paid for income taxes 2 us-gaap_IncomeTaxesPaid us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 5248000 5248 false false 2 true true 4722000 4722 false false 3 true true 1039000 1039 false false No definition available. No authoritative reference available. false false 3 43 false Thousands UnKnown UnKnown false true