Entity tax identification number Entity Tax Identification Number Rollovers (Note 1) EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover Maximum Maximum [Member] Legal Entity [Axis] Legal Entity [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Fair Value of Plan Assets EBP, Fair Value Policy [Policy Text Block] EBP, Fair Value Policy EBP, Description of Plan [Table] EBP, Description of Plan [Table] Mutual funds Mutual Fund [Member] Investment per option, increment requirement EBP, Investment Per Option, Increment Requirement EBP, Investment Per Option, Increment Requirement EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Table] Pretax, maximum annual compensation to total compensation, percentage EBP, Participant Contribution, Pretax, Maximum Annual Compensation to Total Compensation, Percentage Maximum borrowing, amount EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount Investments EBP, Investment, Fair Value and NAV [Text Block] Minimum borrowing, amount EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount Investments, at fair value (Note 4) Total investments, at fair value EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value Retirement age EBP, Retirement Age EBP, Retirement Age Money market fund Money Market Funds [Member] Level 1 Fair Value, Inputs, Level 1 [Member] Plan modification request, maximum period after effective date EBP, Plan Modification Request, Maximum Period After Effective Date EBP, Plan Modification Request, Maximum Period After Effective Date EBP, Investment, Fair Value and NAV [Abstract] Statistical Measurement [Axis] Statistical Measurement [Axis] EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Table] Grandfathered withdrawal option, suspension term EBP, Note Receivable from Participant, Grandfathered Withdrawal Option, Suspension Term EBP, Note Receivable from Participant, Grandfathered Withdrawal Option, Suspension Term Payment of Benefits EBP, Payment to Participant [Policy Text Block] Minimum investment per option, percent EBP, Minimum Investment Per Option, Percent EBP, Minimum Investment Per Option, Percent Amendment Flag Amendment Flag Basis of Presentation EBP, Basis of Accounting [Policy Text Block] EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Table] EBP, Description of Plan and Accounting Change [Abstract] Receivables: EBP, Receivable [Abstract] EBP, Investment, Fair Value and NAV EBP, Investment, Fair Value and NAV [Table Text Block] Voluntary cash-out, rollover or transfer, minimum EBP, Voluntary Cash-Out, Rollover Or Transfer, Minimum EBP, Voluntary Cash-Out, Rollover Or Transfer, Minimum Requisite service period EBP, Requisite Service Period EBP, Requisite Service Period Investments [Domain] Investments [Domain] Common stock of ONE Gas, Inc. EBP, Nonemployer, Common Stock [Member] After tax, maximum annual compensation to total compensation, percentage EBP, Participant Contribution, After Tax, Maximum Annual Compensation to Total Compensation, Percentage EBP, Participant Contribution, After Tax, Maximum Annual Compensation to Total Compensation, Percentage Use of Estimates EBP, Use of Estimate [Policy Text Block] Schedule H, Line 4i - Schedule of Assets (Held at End of Year) EBP, Schedule of Asset Held for Investment [Text Block] Cover [Abstract] Note receivable from participant, primary residence, maximum borrowing term EBP, Note Receivable From Participant, Account, Primary Residence, Maximum Borrowing Term EBP, Note Receivable From Participant, Account, Primary Residence, Maximum Borrowing Term Employer EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash Minimum Minimum [Member] Investment Type [Axis] Investment Type [Axis] Interest income on notes receivable from participants EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant Total contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution Participants EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover Net appreciation in fair value of investments EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment Dividends and interest EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment EBP, Description of Plan [Line Items] EBP, Description of Plan [Line Items] Plan number EBP, Plan Number EBP, Investment, Fair Value and NAV [Line Items] EBP, Investment, Fair Value and NAV [Line Items] Description of the Plan EBP, Description of Plan [Text Block] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] Common stock of ONEOK, Inc. EBP, Employer, Common Stock [Member] EBP, Schedule of Asset Held for Investment [Abstract] EBP, Accounting Policy [Table] EBP, Accounting Policy [Table] Investment income: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment [Abstract] Investment, Identifier [Axis] Investment, Identifier [Axis] Asset held for investment EBP, Asset Held for Investment Document Information [Line Items] Document Information [Line Items] Recently Issued Accounting Standards Update EBP, Recently Issued Accounting Standards Update [Policy Text Block] EBP, Recently Issued Accounting Standards Update Note receivable from participant, maximum number of loans EBP, Note Receivable from Participant, Maximum Number Of Loans EBP, Note Receivable from Participant, Maximum Number Of Loans Participant compensation matched, percentage EBP, Employer Contribution, Participant Compensation Matched, Percentage EBP, Statement of Change in Net Asset Available for Benefit [Abstract] Level 2 Fair Value, Inputs, Level 2 [Member] Participant compensation matched, true-up, percentage EBP, Employer Contribution, Participant Compensation Matched, True-Up, Percentage EBP, Employer Contribution, Participant Compensation Matched, True-Up, Percentage Net increase in net assets available for benefits EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Party-in-Interest Transactions EBP, Related Party and Party-in-Interest Transactions [Text Block] EBP, Related Party and Party-in-Interest Transactions [Abstract] EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Total receivables EBP, Receivable Employer contributions EBP, Employer Contribution, Receivable Automatic deferral rate EBP, Participant Contribution, Automatic, Deferral Rate Automatic deferral rate, annual increase EBP, Participant Contribution, Automatic, Annual Increase Deferral Rate Annual increase in percentage of eligible compensation contributed for participant automatically enrolled in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) until the contribution reaches maximum threshold. Benefits paid to participants EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Total Investments EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] EBP, Statement of Net Asset Available for Benefit [Abstract] Profit sharing, requisite service period EBP, Profit Sharing, Requisite Service Period EBP, Profit Sharing, Requisite Service Period Purchase of common stock, period start after quarterly or annual release EBP, Purchase Of Common Stock, Period Start After Quarterly Or Annual Release EBP, Purchase Of Common Stock, Period Start After Quarterly Or Annual Release EBP, Accounting Policy [Line Items] EBP, Accounting Policy [Line Items] Profit sharing, quarterly fixed rate contribution, percentage EBP, Employer Contribution, Quarterly Fixed Rate Contribution, Profit Sharing, Percentage Fixed rate annual contribution for eligible participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Administrative Costs EBP, Expense [Policy Text Block] Note receivable from participant, maximum withdrawals EBP, Note Receivable from Participant, Maximum Annual Withdrawals EBP, Note Receivable from Participant, Maximum Annual Withdrawals Participant loan, current value EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Investment and Notes Receivable Valuation and Income Recognition EBP, Investment [Policy Text Block] Fair Value, Inputs, Level 1, Level 2, and Level 3 Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] Document Type Document Type Involuntary cash-out limit EBP, Involuntary Cash-out Limit EBP, Involuntary Cash-out Limit Entity Central Index Key Entity Central Index Key Participant loan, interest rate EBP, Asset Held for Investment, Participant Loan, Interest Rate Collective investment trusts Common Collective Trust [Member] Cost charged to participant per common stock purchased (in dollars per share) EBP, Cost Charged To Participant Per Common Stock Purchased EBP, Cost Charged To Participant Per Common Stock Purchased Acquisitions EBP, Acquisitions [Text Block] EBP, Acquisitions Notes receivable from participants EBP, Note Receivable from Participant Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Summary of Significant Accounting Policies EBP, Summary of Accounting Policy [Text Block] Entity Registrant Name Entity Registrant Name Maximum borrowing, to total account, percentage EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage Note receivable from participant, general loan, maximum borrowing term EBP, Note Receivable From Participant, General Loan, Maximum Borrowing Term EBP, Note Receivable From Participant, General Loan, Maximum Borrowing Term Document Information [Table] Document Information [Table] Profit sharing, annual fixed rate contribution, amount EBP, Employer Contribution, Annual Fixed Rate Contribution, Profit Sharing, Amount EBP, Employer Contribution, Annual Fixed Rate Contribution, Profit Sharing, Amount Income Taxes EBP, Income Tax Policy [Policy Text Block] EBP, Income Tax Policy Total investment income EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment EBP, Related Party and Party-in-Interest Transactions [Line Items] EBP, Related Party and Party-in-Interest Transactions [Line Items] Level 3 Fair Value, Inputs, Level 3 [Member] Net assets available for benefits Net assets available for benefits, beginning of period Net assets available for benefits, end of period EBP, Net Asset Available for Benefit EBP 002 EBP 002 [Member] EBP 002 Entity [Domain] Entity [Domain] Contributions: EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] NAV Fair Value Measured at Net Asset Value Per Share [Member] EBP, Investment, Fair Value and NAV [Table] EBP, Investment, Fair Value and NAV [Table] EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Line Items]