Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Noncash Compensation Expense Noncash Compensation Expense [Member] Noncash Compensation Expense Trading Arrangement: Trading Arrangement [Axis] Maximum Maximum [Member] Period following closing for borrowings Debt Instrument, Period Following Closing For Borrowings Debt Instrument, Period Following Closing For Borrowings Statistical Measurement [Domain] Statistical Measurement [Domain] Short-Term Debt, Type [Axis] Short-Term Debt, Type [Axis] Title of 12(b) Security Title of 12(b) Security Net income available to common shareholders - diluted Net Income (Loss) Available to Common Stockholders, Diluted Subsequent Event Subsequent Event [Member] Document Fiscal Year Focus Document Fiscal Year Focus Revenue, remaining performance obligation, expected timing of satisfaction, period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Transaction costs Transaction costs Business Combination, Acquisition-Related Cost, Expense Weighted average interest rate Debt, Weighted Average Interest Rate Derivative Instruments and Hedging Activities [Table] Derivative Instruments, Gain (Loss) [Table] Adjustment to Compensation, Amount Adjustment to Compensation Amount Segment Reporting [Abstract] Segment Reporting [Abstract] Common stock Common Stock, Value, Issued Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Line of Credit Line of Credit [Member] Restatement Determination Date Restatement Determination Date Cash held - offsetting derivative net asset positions under master- netting arrangements Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash, Offset Against Derivative Asset Derivative Instrument Risk [Axis] Derivative Instrument Risk [Axis] Derivative Instrument [Axis] Swing Swaps Swing Swaps [Member] Swing Swaps Effect of dilutive securities Dilutive Securities, Effect on Basic Earnings Per Share Corporate other Other Corporate Costs and Noncash Items Sum of various corporate costs and noncash Items Amendment Flag Amendment Flag Consolidated Entities [Axis] Consolidated Entities [Axis] Current liabilities Liabilities, Current [Abstract] Schedule of Notional Amounts of Derivative Instruments Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Option Indexed to Issuer's Equity, Equity [Table] Option Indexed to Issuer's Equity, Equity [Table] Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax [Abstract] EnLink Acquisition Stock Issued During Period, Value, Acquisitions Consolidated Entities [Domain] Consolidated Entities [Domain] Delaware Basin JV Acquisition Payments to Noncontrolling Interests Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Other Other Unconsolidated Affiliate [Member] ONEOK Partners' equity investment in other unconsolidated affiliates. Entity Address, State or Province Entity Address, State or Province PEO Total Compensation Amount PEO Total Compensation Amount Common stock, shares, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Noncash compensation expense and other Employee Benefit and Share-Based Payment Arrangement, Noncash Capital expenditures Segment Reporting, Long-Lived Asset, Expenditure for Addition Intangible assets, net Intangible Asset, Excluding Goodwill, after Accumulated Amortization Derivative outstanding Derivative, Notional Amount Basic (in shares) Net income attributable to ONEOK available for common stock (in shares) Weighted Average Number of Shares Outstanding, Basic Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Northern Border Northern Border Pipeline [Member] ONEOK Partners' equity investment in Northern Border Pipeline. Intersegment Revenues by Name [Axis] Intersegment Revenues by Name [Axis] Intersegment Revenues by Name Total other assets Investments and Other Noncurrent Assets Number of reportable segments Number of Reportable Segments Total current liabilities Liabilities, Current Short-Term Debt, Type [Domain] Short-Term Debt, Type [Domain] Natural Gas Pipelines Wholly Owned Interstate Natural Gas Pipelines [Member] Wholly Owned Interstate Natural Gas Pipelines Entity Address, City or Town Entity Address, City or Town Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Basis of Accounting Basis of Accounting, Policy [Policy Text Block] Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Net income attributable to ONEOK available for common stock Net Income (Loss) Available to Common Stockholders, Basic Basic EPS Basic EPS from Continuing Operations [Abstract] Basic EPS from Continuing Operations [Abstract] Level 2 Fair Value, Inputs, Level 2 [Member] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] EnLink Acquisition EnLink Acquisition [Member] EnLink Acquisition Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Total other comprehensive income (loss), net of tax Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Current maturities of long-term debt (Note D) Current maturities of long-term debt (Note D) Long-Term Debt, Current Maturities Subsequent Event Type [Axis] Subsequent Event Type [Axis] Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Treasury stock, at cost Treasury Stock, Value Recently Issued Accounting Standards Update New Accounting Pronouncements, Policy [Policy Text Block] Schedule of Segments Segment Reporting [Table Text Block] Noncontrolling Interests Noncontrolling Interest [Member] Change in fair value of derivatives, benefit Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax Revenue, remaining performance obligation, expected timing of satisfaction, period Revenue, Performance Obligation, Remaining Period Revenue, Performance Obligation, Remaining Period Change in retirement and other postretirement benefit plan obligations, tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Long-term debt Long-Term Debt Document Period End Date Document Period End Date Changes in assets and liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Transaction Costs [Domain] Transaction Costs [Domain] Transaction Costs [Domain] Purchased / Payor Purchasor [Member] Information on a derivative contract to purchase, be the payor. Debt, face amount Debt Instrument, Face Amount EQUITY Equity [Text Block] Services and other Services [Member] Services [Member] Security Exchange Name Security Exchange Name Debt instrument, term Debt Instrument, Term Derivative liabilities netting Derivative Liability, Subject to Master Netting Arrangement, Gross Asset and Collateral, Right to Reclaim Cash, Offset Fixed price Fixed Price [Member] Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Impairment of equity investments (Note H) Impairment of equity investments (Note H) Equity Method Investment, Other-than-Temporary Impairment Entity Shell Company Entity Shell Company Consolidation Items [Domain] Consolidation Items [Domain] Accrued interest Interest Payable, Current Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] EARNINGS PER SHARE Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Risk-management assets and liabilities AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax Earnings Per Share [Abstract] Earnings Per Share [Abstract] Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Document Fiscal Period Focus Document Fiscal Period Focus Segment adjusted EBITDA Adjusted EBITDA Net income adjusted for interest expense, depreciation and amortization, noncash impairment charges, income taxes and AFUDC and other noncash items. 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Contributions to unconsolidated affiliates Capital expenditures (less allowance for equity funds used during construction) Payments to Acquire Interest in Subsidiaries and Affiliates Credit Facility [Domain] Credit Facility [Domain] Compensation Amount Outstanding Recovery Compensation Amount Liquids commodity sales Liquids Commodity [Member] Liquids Commodity Individual: Individual [Axis] Diluted (in shares) Net income attributable to ONEOK available for common stock and common stock equivalents (in shares) Weighted Average Number of Shares Outstanding, Diluted Common stock dividends (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid Entity Emerging Growth Company Entity Emerging Growth Company Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Derivative, nonmonetary notional amount, volume Derivative, Nonmonetary Notional Amount, Volume Underlying Security Market Price Change Underlying Security Market 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Value, Inputs, Level 1 [Member] Exchange services and natural gas gathering and processing revenue Exchange Services and Natural Gas Gathering and Processing Revenue [Member] Exchange Services and Natural Gas Gathering and Processing Revenue Organization, Consolidation and Presentation of Financial Statements [Abstract] Determining Fair Value Fair Value of Financial Instruments, Policy [Policy Text Block] Derivative asset, fair value, gross Derivative Asset, Gross Asset Including Not Subject to Master Netting Arrangement All Executive Categories All Executive Categories [Member] Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Long-term debt, fair value Long-Term Debt, Fair Value Redeemable noncontrolling interests in consolidated subsidiaries (Note F) Beginning balance Ending balance Redeemable Noncontrolling Interest, Equity, Carrying Amount Commodity sales Commodity Sales [Member] Commodity Sales [Member] Schedule of Computation of Basic and Diluted EPS Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Other and Eliminations Eliminations And Reconciling Items [Member] Eliminations And Reconciling Items Debt Disclosure [Abstract] Debt Disclosure [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] SEGMENTS Segment Reporting [Text Block] Common stock issued Stock Issued During Period, Value, Other Minimum Minimum [Member] Expiration Date Trading Arrangement Expiration Date Transportation and storage revenue Transportation and Storage Revenue [Member] Transportation and Storage Revenue Hedging Relationship [Axis] Hedging Relationship [Axis] Derivative liability, fair value, gross Derivative Liability, Gross Liability Including Not Subject to Master Netting Arrangement Derivative liabilities Liabilities: Liabilities [Abstract] VARIABLE INTEREST ENTITIES Variable Interest Entity Disclosure [Text Block] Location, Statement of Income, Balance [Axis] Location, Statement of Income, Balance [Axis] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Total equity Beginning balance Ending balance Equity, Including Portion Attributable to Noncontrolling Interest Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Natural Gas Liquids Natural Gas Liquids [Member] Natural Gas Liquids Common stock dividends Dividends, Common Stock Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Common stock, shares, authorized (in shares) Common Stock, Shares Authorized Exercise Price Award Exercise Price Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Segment Reporting [Line Items] Segment Reporting [Line Items] Document Quarterly Report Document Quarterly Report Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Segments [Domain] Segments [Domain] DEBT Debt Disclosure [Text Block] Extinguishment of long-term debt (Note D) Repayments of Long-Term Debt Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Investments in unconsolidated affiliates Investments in unconsolidated affiliates Equity Method Investments Equity Component [Domain] Equity Component [Domain] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Secured Debt Secured Debt [Member] Adoption Date Trading Arrangement Adoption Date Interest rate Debt Instrument, Interest Rate, Stated Percentage Total ONEOK shareholders' equity Equity, Attributable to Parent Assets Derivative assets Assets [Abstract] Title Trading Arrangement, Individual Title Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Accounting Policies [Abstract] Accounting Policies [Abstract] Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Insider Trading Policies and Procedures [Line Items] Cash posted - total Derivative, Collateral, Right to Reclaim Cash, Total Amount of right to receive cash collateral under master netting arrangements. Other, net Proceeds from (Payment for) Other Financing Activity Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Deferred income taxes Deferred Income Tax Expense (Benefit) Repayments of debt Repayments of Debt Business Combination [Domain] Business Combination [Domain] COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Residue natural gas sales Residue Natural Gas Sales [Member] Residue Natural Gas Sales Entity Central Index Key Entity Central Index Key Accumulated depreciation and amortization Property, Plant, and Equipment, Accumulated Depreciation, Depletion, and Amortization All Adjustments to Compensation All Adjustments to Compensation [Member] Other, net Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Other Item Business Combination [Axis] Business Combination [Axis] Equity (Note E) Equity [Abstract] Equity [Abstract] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Operating costs Direct Operating Costs Other, net Stockholders' Equity, Other Contributions from redeemable noncontrolling interests (Note F) Temporary Equity, Carrying Amount, Period Increase (Decrease) Income Statement [Abstract] Income Statement [Abstract] Document Transition Report Document Transition Report Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Investment, Name [Axis] Investment, Name [Axis] Derivatives designated as hedging instruments Derivatives designated as hedging instruments: Designated as Hedging Instrument [Member] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Debt instrument, basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate City Area Code City Area Code Indebtedness to adjusted EBITDA, maximum from acquisitions Debt Instrument, Covenant, Indebtedness To Adjusted EBITDA, Maximum From Acquisitions Indebtedness To Adjusted EBITDA Maximum From Acquisitions AOCL AOCI Attributable to Parent [Member] All Individuals All Individuals [Member] Dividends paid Payments of Dividends Name Forgone Recovery, Individual Name Overland Pass Overland Pass Pipeline Company [Member] ONEOK Partners' equity investment in Overland Pass Pipeline Company Natural Gas Gathering and Processing Intersegment Natural Gas Gathering and Processing Intersegment [Member] Natural Gas Gathering and Processing Intersegment Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Statement [Line Items] Statement [Line Items] Total assets Assets Operating Segments Operating Segments [Member] Transaction Costs [Axis] Transaction Costs [Axis] Transaction Costs Interest expense Interest expense, net of capitalized interest Interest Expense, Nonoperating PEO PEO [Member] Powder Springs Logistics, LLC Powder Springs Logistics, LLC [Member] Powder Springs Logistics, LLC Other deferred credits Other deferred credits Other Liabilities, Noncurrent Goodwill Goodwill Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Subsequent Event Type [Domain] Subsequent Event Type [Domain] Retained Earnings Retained Earnings [Member] Revolving Credit Facility Revolving Credit Facility [Member] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Common stock, shares, outstanding (in shares) Common Stock, Shares, Outstanding Award Timing Disclosures [Line Items] Diluted EPS (Note G) (in dollars per share) Net income attributable to ONEOK available for common stock and common stock equivalents (in dollars per share) Earnings Per Share, Diluted Entity Current Reporting Status Entity Current Reporting Status Cash used in financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Total Shareholder Return Amount Total Shareholder Return Amount Adjusted EBITDA from unconsolidated affiliates Adjusted EBITDA, Unconsolidated Affiliates Adjusted EBITDA, Unconsolidated Affiliates Cash Flow Hedging Cash Flow Hedging [Member] Capitalized interest Interest Costs Capitalized Adjustments to reconcile net income to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] - Natural gas (Bcf) Natural Gas [Member] Gain (loss) on disposition of property plant equipment Equity Method Investment, Difference Between Carrying Amount and Underlying Equity Net property, plant and equipment Net property, plant and equipment Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization Total revenues (Note J) Total revenues Revenue from Contract with Customer, Excluding Assessed Tax Schedule of Cash Flow Hedging Instruments Effect on Income (Loss) Schedule of Cash Flow Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Schedule of Equity Method Investments Equity Method Investments [Table Text Block] Derivative assets Derivative Asset Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Underlying Securities Award Underlying Securities Amount Less: Comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest REVENUES Revenue from Contract with Customer [Text Block] Derivative positon, by transaction type [Axis] Derivative positon, by transaction type [Axis] Derivatives, by Commodity [Axis] Derivatives, by Commodity [Axis] Preferred Stock Preferred Stock [Member] Other, net Payment for (Proceeds from) Other Investing Activity Inventories, net of commodity imbalances Increase (Decrease) in Inventories 5.55% Notes Payable Due 2026 5.55% Notes Payable Due 2026 [Member] 5.55% Notes Payable Due 2026 Segment Reporting [Table] Segment Reporting [Table] Net income Temporary Equity, Net Income Schedule of Equity Method Investments [Table] Equity Method Investment [Table] Investing activities Cash Provided by (Used in) Investing Activity, Continuing Operation [Abstract] Other current assets Other Assets, Current Operating activities Cash Provided by (Used in) Operating Activity, Continuing Operation [Abstract] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] All Trading Arrangements All Trading Arrangements [Member] Other Performance Measure, Amount Other Performance Measure, Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Derivative amounts reclassified to net income, tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax Operating income Operating Income (Loss) Revenue, remaining performance obligation, amount Revenue, Remaining Performance Obligation, Amount Current Fiscal Year End Date Current Fiscal Year End Date Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Derivative [Line Items] Derivative [Line Items] Number of borrowings within 90 days of closing date, maximum Debt Instrument, Number Of Borrowings Within 90 Days Of Closing Date, Maximum Debt Instrument, Number Of Borrowings Within 90 Days Of Closing Date, Maximum Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Common stock, dividends, declared (in dollars per share) Common Stock, Dividends, Per Share, Declared Entity File Number Entity File Number Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Short-term borrowings, net Proceeds from (Repayments of) Short-Term Debt Futures and Swaps Futures and Swaps [Member] Futures and Swaps Indebtedness to adjusted EBITDA, current Indebtedness To Adjusted Ebitda, Current Total debt to earnings before interest, taxes, depreciation and amortization at period end. Distributions to noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Total change in fair value of cash flow hedges reclassified from accumulated other comprehensive loss into net income on derivatives Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax General taxes Taxes, Other Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Common stock, shares, issued (in shares) Common Stock, Shares, Issued Measure: Measure [Axis] UNCONSOLIDATED AFFILIATES Equity Method Investments and Joint Ventures Disclosure [Text Block] Schedule of Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] Treasury stock, shares (in shares) Treasury Stock, Common, Shares Equity Components [Axis] Equity Components [Axis] Operations and maintenance Other Cost and Expense, Operating Product and Service [Domain] Product and Service [Domain] Entity Interactive Data Current Entity Interactive Data Current Less: Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Deferred income taxes Deferred Income Tax Liabilities, Net Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] BridgeTex BridgeTex [Member] BridgeTex Entity Small Business Entity Small Business Advisory Fees and Severance Advisory Fees and Severance [Member] Advisory Fees and Severance Comprehensive income attributable to ONEOK Comprehensive Income (Loss), Net of Tax, Attributable to Parent Decrease to indebtedness to adjusted EBITDA Indebtedness to Adjusted EBITDA Maximum Total debt to earnings before interest, taxes, depreciation and amortization maximum. Termination Date Trading Arrangement Termination Date Fair Value, Assets and Liabilities Measured on Recurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Changes in benefit plan obligations and other, net of tax of $—, $—, $— and $—, respectively Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Other current liabilities Other Liabilities, Current Other assets Other Assets, Noncurrent Financing activities Cash Provided by (Used in) Financing Activity, Continuing Operation [Abstract] Document Type Document Type Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value as of Grant Date Award Grant Date Fair Value SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Significant Accounting Policies [Text Block] Increase (Decrease) in Temporary Equity [Roll Forward] Increase (Decrease) in Temporary Equity [Roll Forward] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Arrangement Duration Trading Arrangement Duration Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Local Phone Number Local Phone Number Consolidation Items [Axis] Consolidation Items [Axis] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Income before income taxes Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Commitments and contingencies (Note I) Commitments and Contingencies Property, plant and equipment Property, Plant, and Equipment, before Accumulated Depreciation, Depletion, and Amortization Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Equity in net earnings from investments (Note H) Equity in net earnings from investments (Note H) Equity in net earnings from investments Equity in net earnings from investments Equity in net earnings from investments Income (Loss) from Equity Method Investments Roadrunner Roadrunner Gas Transmission [Member] ONEOK Partners' equity method investment in Roadrunner Gas Transmission Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Executive Category: Executive Category [Axis] 4.85% Senior Notes Due July 2026 4.85% Senior Notes Due July 2026 [Member] 4.85% Senior Notes Due July 2026 Liabilities, redeemable noncontrolling interests and equity Liabilities and Equity [Abstract] Schedule of Recurring Fair Value Measurements Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Derivative instrument, by method for setting notional amount [Domain] Derivative instrument, by method for setting notional amount [Domain] Derivative instrument, by method for setting notional amount [Domain] Inventories Inventory, Net All Award Types Award Type [Domain] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount FAIR VALUE MEASUREMENTS Fair Value Disclosures [Text Block] Variable Interest Entity [Table] Variable Interest Entity [Table] Level 3 Fair Value, Inputs, Level 3 [Member] Derivative amounts reclassified to net income, net of tax of $(66), $(2), $(85) and $(5), respectively Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax Redemption price, percentage of principal amount redeemed Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Powder Springs Powder Springs [Member] Powder Springs PEO Name PEO Name Deferred credits and other liabilities Deferred Credits and Other Liabilities [Abstract] Matterhorn Matterhorn [Member] Matterhorn Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Entity Tax Identification Number Entity Tax Identification Number Derivative Instruments and Hedging Activities Disclosures [Table] Derivative Instruments and Hedging Activities Disclosures [Table] Change in fair value of derivatives, net of tax of $(7), $(17), $84 and $(6), respectively Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax Repurchase of common stock Treasury Stock, Value, Acquired, Cost Method Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Accounts payable Increase (Decrease) in Accounts Payable Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Non-NEOs Non-NEOs [Member] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Debt Instrument [Axis] Debt Instrument [Axis] Ownership percentage Equity Method Investment, Ownership Percentage Unconsolidated entities expenses in transactions Related Party Transaction, Amounts of Transaction Equity Method Investee, Name [Domain] Investment, Name [Domain] Investment, Name [Domain] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Derivative instrument, by method for setting notional amount [Axis] Derivative instrument, by method for setting notional amount [Axis] The method for setting the notional amount of the derivative instrument. Schedule of Fair Value of Derivatives Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Basic EPS (Note G) (in dollars per share) Net income attributable to ONEOK available for common stock (in dollars per share) Earnings Per Share, Basic Texas City Logistics Texas City Logistics [Member] Texas City Logistics Intersegment Revenues by Name [Domain] Intersegment Revenues by Name [Domain] Intersegment Revenues by Name [Domain] Natural Gas Gathering and Processing Natural Gas Gathering And Processing [Member] Natural Gas Gathering and Processing Total current assets Assets, Current Statistical Measurement [Axis] Statistical Measurement [Axis] Insider Trading Arrangements [Line Items] Long-term debt, excluding current maturities Long-Term Debt, Excluding Current Maturities Cost of sales and fuel (exclusive of items shown separately below) Cost of sales and fuel (exclusive of depreciation and operating costs) Cost of Revenue Award Type Award Type [Axis] Unrealized gains (losses) Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax Interest-rate contracts (Billions of dollars) Interest-rate contracts Interest Rate Contract [Member] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Retained earnings Retained Earnings (Accumulated Deficit) Commodity contracts Commodity contracts Commodity Contract [Member] Product and Service [Axis] Product and Service [Axis] Equity (Note G) Partners' Capital [Abstract] Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Contributions from noncontrolling interests Minority Interest Increase From Contributions By Noncontrolling Interest Holders Minority Interest Increase From Contributions By Noncontrolling Interest Holders Common Stock Common Stock [Member] 1.2 Billion Term Loan Agreement borrowings Proceeds from Issuance of Secured Debt Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Cover [Abstract] Other assets Investments and Other Assets [Abstract] Derivative Contract [Domain] Derivative Contract [Domain] Equity Awards Adjustments Equity Awards Adjustments [Member] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Hedging Relationship [Domain] Hedging Relationship [Domain] Total liabilities, redeemable noncontrolling interests and equity Liabilities and Equity Derivatives, by Commodity [Domain] Derivatives, by Commodity [Domain] Derivatives, by Commodity [Domain] Employee Stock Option Share-Based Payment Arrangement, Option [Member] Noncontrolling interests in consolidated subsidiaries Equity, Attributable to Noncontrolling Interest Sold / Receiver Sellor [Member] Information on a derivative contract to sell, be the reciever. Segments [Axis] Segments [Axis] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Tabular List, Table Tabular List [Table Text Block] Paid-in capital Additional Paid in Capital Other income, net Other Nonoperating Income (Expense) Term Loan Agreement Term Loan Agreement [Member] Term Loan Agreement Other operating expense (income), net Other Operating Income (Expense), Net Name Awards Close in Time to MNPI Disclosures, Individual Name Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Option Indexed to Issuer's Equity [Line Items] Option Indexed to Issuer's Equity [Line Items] Property, plant and equipment Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization [Abstract] Accounts receivable, net Receivables, Net, Current Adjustment to Compensation: Adjustment to Compensation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Hedging Designation [Axis] Hedging Designation [Axis] Delaware Basin JV Acquisition Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Credit Facility [Axis] Credit Facility [Axis] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Name Measure Name Saddlehorn Saddlehorn [Member] Saddlehorn Accounts payable Accounts Payable, Current Pay vs Performance Disclosure [Line Items] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Debt Instrument [Line Items] Debt Instrument [Line Items] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Paid-in Capital Additional Paid-in Capital [Member] Entity Filer Category Entity Filer Category Eiger Eiger [Member] Eiger Derivative assets netting Derivative Asset, Subject to Master Netting Arrangement, Gross Liability and Collateral, Obligation to Return Cash, Offset Name Trading Arrangement, Individual Name Cash and cash equivalents Cash and cash equivalents Cash and Cash Equivalent Company Selected Measure Amount Company Selected Measure Amount Distributions received from unconsolidated affiliates Proceeds from Equity Method Investment, Distribution Derivatives not designated as hedging instruments Derivatives not designated as hedging instruments: Not Designated as Hedging Instrument [Member] Equity Method Investments and Joint Ventures [Abstract] Equity Method Investments and Joint Ventures [Abstract] Depreciation and amortization Depreciation and amortization Depreciation, Depletion and Amortization - NGLs, Refined Products and crude oil (MMBbl) Crude Oil and Natural Gas Liquids (NGL) [Member] Basis Basis [Member] Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Current assets Assets, Current [Abstract] Refined Products and Crude Refined Products and Crude Oil Refined Products and Crude Oil [Member] Refined Products and Crude Oil Derivative liabilities Derivative Liability Non-PEO NEO Non-PEO NEO [Member] Senior Notes Senior Notes [Member] Entity Address, Address Line One Entity Address, Address Line One Income taxes Income Tax Expense (Benefit) Net income Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Award Timing Method Award Timing Method [Text Block] Change in cash and cash equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Net income attributable to ONEOK Net Income (Loss) Attributable to Parent Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Balance Sheet Location [Axis] Location, Statement of Financial Position, Balance [Axis] Statement [Table] Statement [Table] Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment [Member] Restatement Determination Date: Restatement Determination Date [Axis] Schedule of Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block] Total deferred credits and other liabilities Liabilities, Other than Long-Term Debt, Noncurrent Derivative Instruments and Hedging Activities Disclosures [Line Items] Derivative Instruments and Hedging Activities Disclosures [Line Items] Accounts receivable Increase (Decrease) in Receivables Assets Derivative Asset, Subject to Master Netting Arrangement, before Offset Revenues Revenues [Abstract] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract]