XML 94 R59.htm IDEA: XBRL DOCUMENT
v3.10.0.1

DEBT (Details) $ in Thousands | 9 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Sep. 30, 2017 USD ($) Rate | Dec. 31, 2018 USD ($) Rate | Dec. 31, 2017 USD ($) Rate | Dec. 31, 2016 USD ($) Rate | Sep. 30, 2018 USD ($) Rate
Debt Instrument [Line Items] |  |  |  |  |
Impairment of long-lived assets |  | $ 0 | $ 15,970 | $ 0 |
Total debt |  | 9,451,354 | 9,198,677 |  |
Unamortized portion of terminated swaps |  | 16,750 | 18,468 |  |
Unamortized debt issuance costs and discounts |  | (87,120) | (78,193) |  |
Current maturities of long-term debt |  | (507,650) | (432,650) |  |
Short-term borrowings |  | 0 | (614,673) |  |
Long-term debt |  | 8,873,334 | 8,091,629 |  |
Senior Notes, Noncurrent | $ 1,200,000 | 1,250,000 |  |  |
Long-term Debt, by Maturity [Abstract] |  |  |  |  |
2019 |  | 507,700 |  |  |
2020 |  | 307,700 |  |  |
2021 |  | 557,700 |  |  |
2022 |  | 1,453,300 |  |  |
2023 |  | 925,000 |  |  |
$2.5 Billion Credit Agreement [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Letters of Credit Outstanding, Amount |  | 1,400 | 15,800 |  |
Line of credit facility sublimit |  | 100,000 |  |  |
Line of Credit Facility Swingline Subfacility |  | 200,000 |  |  |
Line Of Credit Facility Option To Increase Borrowing Capacity |  | $ 3,500,000 |  |  |
Line of Credit Facility, Interest Rate Description |  | borrowings, if any, will accrue at LIBOR plus 110 basis points |  |  |
Line Of Credit Facility, Annual Facility Fee Description |  | the annual facility fee is 15 basis points |  |  |
Indebtedness To Adjusted Ebitda Current |  | 3.5 |  |  |
$2.5 Billion Credit Agreement [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument covenant description |  | Among other things, these covenants include maintaining a ratio of indebtedness to adjusted EBITDA (EBITDA, as defined in our $2.5 Billion Credit Agreement, adjusted for all noncash charges and increased for projected EBITDA from certain lender-approved capital expansion projects). At December 31, 2018, due to our acquisition of the remaining 20 percent interest in WTLPG for $195 million, the covenant increased to 5.5 to 1 for the second half of 2018 and first quarter 2019, and 5.0 to 1 thereafter. Our $2.5 Billion Credit Agreement includes a $100 million sublimit for the issuance of standby letters of credit and a $200 million sublimit for swingline loans. Under the terms of our $2.5 Billion Credit Agreement, we may request an increase in the size of the facility to an aggregate of $3.5 billion by either commitments from new lenders or increased commitments from existing lenders. Our $2.5 Billion Credit Agreement contains provisions for an applicable margin rate and an annual facility fee, both of which adjust with changes in our credit ratings. Based on our current credit ratings, borrowings, if any, will accrue at LIBOR plus 110 basis points, and the annual facility fee is 15 basis points. We have the option to request an additional one-year extension, subject to lender approval, which may be used for working capital, capital expenditures, acquisitions and mergers, the issuance of letters of credit and for other general corporate purposes. At December 31, 2018, our ratio of indebtedness to adjusted EBITDA was 3.5 to 1, and we were in compliance with all covenants under our $2.5 Billion Credit Agreement. |  |  |
Senior Notes [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Senior Notes, Noncurrent |  |  |  |  | $ 1,250,000
Proceeds from Debt, Net of Issuance Costs | 1,180,000 | $ 1,230,000 |  |  |
Note Payable from Public Offering Due 2018 [Member] |  |  |  |  |
Long-term Debt, by Maturity [Abstract] |  |  |  |  |
2019 |  | 500,000 |  |  |
Notes Payables due 2019 [Member] |  |  |  |  |
Long-term Debt, by Maturity [Abstract] |  |  |  |  |
2020 |  | 300,000 |  |  |
Note Payable from Public Offering Due 2020 [Member] |  |  |  |  |
Long-term Debt, by Maturity [Abstract] |  |  |  |  |
2021 |  | 550,000 |  |  |
Note Payable Due 2022 [Domain] |  |  |  |  |
Long-term Debt, by Maturity [Abstract] |  |  |  |  |
2022 |  | 1,447,400 |  |  |
Note Payable 2 from Public Offering Due 2022 [Member] |  |  |  |  |
Long-term Debt, by Maturity [Abstract] |  |  |  |  |
2023 |  | $ 925,000 |  |  |
Guardian Pipeline [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument covenant description |  | Guardian Pipeline’s senior notes contain financial covenants that require the maintenance of certain financial ratios as defined in the master shelf agreement based on Guardian Pipeline’s financial position and results of operations. Upon any breach of these covenants, all amounts outstanding under the master shelf agreement may become due and payable immediately |  |  |
Debt Instrument, Covenant Compliance |  | At December 31, 2018, Guardian Pipeline was in compliance with its financial covenants |  |  |
Guardian Pipeline [Member] | Notes Payables 1 due 2022 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 28,957 | 36,607 |  |
Average interest rate (in hundredths) | Rate |  | 7.85% |  |  |
Long-term Debt, by Maturity [Abstract] |  |  |  |  |
2019 |  | $ 7,700 |  |  |
2020 |  | 7,700 |  |  |
2021 |  | 7,700 |  |  |
2022 |  | 5,900 |  |  |
2023 |  | 0 |  |  |
Subsidiary Issuer [Member] | Notes Payable due 2016 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  |  |  | $ 450,000 |
Interest rates (in hundredths) | Rate |  |  |  | 6.15% |
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2017 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Repayment of Senior Notes | $ 400,000 |  |  |  |
Interest rates (in hundredths) | Rate | 2.00% |  |  |  |
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2018 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 0 | 425,000 |  |
Repayment of Senior Notes |  |  |  |  | $ 425,000
Interest rates (in hundredths) | Rate |  | 3.20% |  |  | 3.20%
Subsidiary Issuer [Member] | Notes Payables due 2019 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 500,000 | 500,000 |  |
Interest rates (in hundredths) | Rate |  | 8.625% |  |  |
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2020 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 300,000 | 300,000 |  |
Interest rates (in hundredths) | Rate |  | 3.80% |  |  |
Subsidiary Issuer [Member] | Term Loan Agreement due 2019 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 0 | $ 500,000 |  |
Repayment of Senior Notes | $ 500,000 |  |  |  |
Delayed-Draw Unsecured Senior Term Loan |  |  |  | $ 1,000,000 |
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate | Rate |  |  | 2.87% |  |
Subsidiary Issuer [Member] | Note Payable 2 from Public Offering Due 2022 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 900,000 | $ 900,000 |  |
Interest rates (in hundredths) | Rate |  | 3.375% |  |  |
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2023 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 425,000 | 425,000 |  |
Interest rates (in hundredths) | Rate |  | 5.00% |  |  |
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2025 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 500,000 | 500,000 |  |
Interest rates (in hundredths) | Rate |  | 4.90% |  |  |
Subsidiary Issuer [Member] | Notes Payables due 2036 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 600,000 | 600,000 |  |
Interest rates (in hundredths) | Rate |  | 6.65% |  |  |
Subsidiary Issuer [Member] | Notes Payables due 2037 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 600,000 | 600,000 |  |
Interest rates (in hundredths) | Rate |  | 6.85% |  |  |
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2041 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 650,000 | 650,000 |  |
Interest rates (in hundredths) | Rate |  | 6.125% |  |  |
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2043 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 400,000 | 400,000 |  |
Interest rates (in hundredths) | Rate |  | 6.20% |  |  |
Parent Company |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Commercial Paper |  | $ 0 | $ 614,673 |  |
Short-term Debt, Weighted Average Interest Rate, at Point in Time | Rate |  | 2.85% | 2.23% |  |
Parent Company | Senior Notes [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument covenant description |  | Our senior notes are governed by indentures containing covenants, including among other provisions, limitations on our ability to place liens on our property or assets and to sell and leaseback our property. The indentures governing our 6.875 percent senior notes due 2028 include an event of default upon acceleration of other indebtedness of $15 million or more, and the indentures governing the remainder of our senior notes include an event of default upon the acceleration of other indebtedness of $100 million or more. Such events of default would entitle the trustee or the holders of 25 percent in aggregate principal amount of the outstanding senior notes to declare those senior notes immediately due and payable in full. The indenture for the 7.5 percent notes due 2023 also contains a provision that allows the holders of the notes to require ONEOK to offer to repurchase all or any part of their notes if a change of control and a credit rating downgrade occur at a purchase price of 101 percent of the principal amount, plus accrued and unpaid interest, if any. |  |  |
Debt instrument call feature |  | We may redeem our senior notes, in whole or in part, at any time prior to their maturity at a redemption price equal to the principal amount, plus accrued and unpaid interest and a make-whole premium. We may redeem the balance of our senior notes due 2020, 2022, 2023, 2025, 2027, 2028 (4.55%), 2041, 2043, 2047 and 2048 at a redemption price equal to the principal amount, plus accrued and unpaid interest, starting one to six months before the maturity date as stipulated in the respective contract terms. Our senior notes are senior unsecured obligations, ranking equally in right of payment with all of our existing and future unsecured senior indebtedness. |  |  |
Parent Company | Term Loan Agreement due 2021 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Interest Rate Terms |  | bears interest at LIBOR plus 112.5 basis points |  |  |
Total debt |  | $ 550,000 | $ 0 |  |
Parent Company | Note Payable from Public Offering Due 2022 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 547,397 | 547,397 |  |
Interest rates (in hundredths) | Rate |  | 4.25% |  |  |
Parent Company | Note Payable Due 2023 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 500,000 | 500,000 |  |
Interest rates (in hundredths) | Rate |  | 7.50% |  |  |
Parent Company | Note Payable Due 2027 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt | $ 500,000 | $ 500,000 | 500,000 |  |
Interest rates (in hundredths) | Rate | 4.00% | 4.00% |  |  |
Parent Company | Note Payables 1 due 2028 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 800,000 | 0 |  |
Repayment of Senior Notes | $ 87,000 |  |  |  |
Interest rates (in hundredths) | Rate | 6.50% | 4.55% |  |  |
Parent Company | Note Payables 2 due 2028 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 100,000 | 100,000 |  |
Interest rates (in hundredths) | Rate |  | 6.875% |  |  |
Parent Company | Note Payable from Public Offering Due 2028 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  |  |  |  | $ 800,000
Interest rates (in hundredths) | Rate |  |  |  |  | 4.55%
Parent Company | Notes Payables due 2035 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 400,000 | 400,000 |  |
Interest rates (in hundredths) | Rate |  | 6.00% |  |  |
Parent Company | Notes Payables due 2047 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt | $ 700,000 | $ 700,000 | 700,000 |  |
Interest rates (in hundredths) | Rate | 4.95% | 4.95% |  |  |
Parent Company | Note Payable from Public Offering Due 2047 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  |  |  |  | $ 450,000
Interest rates (in hundredths) | Rate |  |  |  |  | 5.20%
Parent Company | Note Payables due 2048 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Total debt |  | $ 450,000 | $ 0 |  |
Interest rates (in hundredths) | Rate |  | 5.20% |  |  |
Parent Company | Term Loan Agreement due 2019 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate | Rate |  | 3.63% |  |  |

X
- Definition Delayed-Draw Unsecured Senior Term Loan + References No definition available. + Details
Name: | oke_DelayedDrawUnsecuredSeniorTermLoan
Namespace Prefix: | oke_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Total debt to earnings before interest, taxes, depreciation and amortization at period end. + References No definition available. + Details
Name: | oke_IndebtednessToAdjustedEbitdaCurrent
Namespace Prefix: | oke_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Description of annual fees under the credit under the credit facility + References No definition available. + Details
Name: | oke_LineOfCreditFacilityAnnualFacilityFeeDescription
Namespace Prefix: | oke_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition This item represents the total amount the facility may increase to. + References No definition available. + Details
Name: | oke_LineOfCreditFacilityOptionToIncreaseBorrowingCapacity
Namespace Prefix: | oke_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This item represents the amount of sublimit for the issuance of standby letters of credit. + References No definition available. + Details
Name: | oke_LineOfCreditFacilitySublimit
Namespace Prefix: | oke_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line of credit facility swingline subfacility + References No definition available. + Details
Name: | oke_LineofCreditFacilitySwinglineSubfacility
Namespace Prefix: | oke_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Repayment of long-term debt or senior notes + References No definition available. + Details
Name: | oke_RepaymentofSeniorNotes
Namespace Prefix: | oke_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Unamortized portion of terminated interest rate swaps + References No definition available. + Details
Name: | oke_UnamortizedPortionofTerminatedSwaps
Namespace Prefix: | oke_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)(a)(3)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)(2)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_CommercialPaper
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Description of a feature that permits the issuer of the debt to repay or convert it before the stated maturity date (early retirement date). The description may include such items as the call price, the period that the issuer can call the debt, including the earliest call date, and other significant terms of the call feature, which may include the debt holders' ability to convert the debt to equity if the call option is exercised and contingent events that trigger the issuer's ability to call the debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(5)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentCallFeature
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition States whether the entity was in compliance with the debt covenants throughout the reporting period, and describes facts and circumstances of any compliance failure. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823 + Details
Name: | us-gaap_DebtInstrumentCovenantCompliance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Description of minimum financial levels (for example, tangible net worth and working capital) and achievement of certain financial ratios (for example, working capital ratio and debt service coverage ratio), and adherence to certain clauses which generally require or restrict certain actions (for example, entering into a debt arrangement with equal or greater seniority, and selling or discontinuing a certain business segment or material subsidiary) to be in compliance with the covenant clauses of the debt agreement. May also include a discussion of the adverse consequences that would result if the entity violates or fails to satisfy the covenants. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823 + Details
Name: | us-gaap_DebtInstrumentCovenantDescription
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateTerms
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of unamortized debt discount (premium) and debt issuance costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399 + Details
Name: | us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 958 -SubTopic 225 -Section 45 -Paragraph 11 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84241808&loc=d3e92212-112881 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84176398&loc=d3e2921-110230 + Details
Name: | us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. + References No definition available. + Details
Name: | us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Description of the interest rate for the amounts borrowed under the credit facility, including the terms and the method for determining the interest rate (for example, fixed or variable, LIBOR plus a percentage, increasing rate, timing of interest rate resets, remarketing provisions). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityInterestRateDescription
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_LongTermDebtByMaturityAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19,20) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebtCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebtNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebtPercentageBearingVariableInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average interest rate of long-term debt outstanding calculated at point in time. + References No definition available. + Details
Name: | us-gaap_LongtermDebtWeightedAverageInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination. + References No definition available. + Details
Name: | us-gaap_ProceedsFromDebtNetOfIssuanceCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_SeniorLongTermNotes
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)(a)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)(a)(1)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_ShortTermBorrowings
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Weighted average interest rate of short-term debt outstanding calculated at point in time. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_ShortTermDebtWeightedAverageInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_LineOfCreditFacilityAxis=oke_ONEOKCreditAgreement2017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LineOfCreditFacilityAxis=oke_A2.5BillionCreditAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=us-gaap_SeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayablefromPublicOfferingDue2018Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotesPayablesDue2019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayablefromPublicOfferingDue2020Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayableDue2021Domain
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayable2fromPublicOfferingDue2022Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=oke_GuardianPipelineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotesPayables1Due2022Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConsolidatedEntitiesAxis=us-gaap_SubsidiaryIssuerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotesPayableDue2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayableFromPublicOfferingDue2017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_TermLoanAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayablefromPublicOfferingDue2023Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayablefromPublicOfferingDue2025Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotesPayablesDue2036Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotesPayablesDue2037Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayableFromPublicOfferingDue2041Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayablefromPublicOfferingDue2043Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConsolidatedEntitiesAxis=us-gaap_ParentCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_TermLoanAgreementdue2021Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayableFromPublicOfferingDue2022Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayableDue2023Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayableDue2027Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayables1Due2028Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayables2Due2028Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayablefromPublicOfferingDue2028Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotesPayablesDue2035Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotesPayablesdue2047Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayablefromPublicOfferingDue2048Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=oke_NotePayablesdue2048Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |