Less than 1 EBP, Less Than One Year [Member] EBP, Less Than One Year Entity tax identification number Entity Tax Identification Number Rollover EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover Maximum Maximum [Member] Forfeited nonvested account, decrease from administrative expense EBP, Forfeited Nonvested Account, Decrease from Administrative Expense Legal Entity [Axis] Legal Entity [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] EBP, Description of Plan [Table] EBP, Description of Plan [Table] Mutual funds Mutual Fund [Member] Participant Contribution Receivables EBP, Participant Contribution Receivables [Policy Text Block] EBP, Participant Contribution Receivables EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Table] EBP 003 EBP 003 [Member] EBP 003 Total deductions EBP, Change in Net Asset Available for Benefit, Decrease Maximum borrowing, amount EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount Fair Value Measurements EBP, Investment, Fair Value and NAV [Text Block] Minimum borrowing, amount EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount Number of distributions in process EBP, Number Of Distributions In Process EBP, Number Of Distributions In Process Total investments EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value EBP, Vesting Period [Domain] EBP, Vesting Period [Domain] EBP, Vesting Period [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] NAV per share (in dollars per share) EBP, Net Asset Value per Share or Unit Vested Percentage EBP, Employer Contribution Vesting Percentage EBP, Employer Contribution Vesting Percentage EBP, Investment, Fair Value and NAV [Abstract] Total assets EBP, Asset ASSETS EBP, Asset [Abstract] Statistical Measurement [Axis] Statistical Measurement [Axis] Additions to net assets: EBP, Change in Net Asset Available for Benefit, Increase [Abstract] EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Table] Payment of Benefits EBP, Payment to Participant [Policy Text Block] Recent Accounting Pronouncements EBP, Recent Accounting Pronouncements [Policy Text Block] EBP, Recent Accounting Pronouncements Amendment Flag Amendment Flag Basis of Accounting EBP, Basis of Accounting [Policy Text Block] EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Table] Number of shares held by Plan (in shares) Origin Bancorp, Inc. Common Stock, number of shares (in shares) EBP, Investment, Number of Shares EBP, Description of Plan and Accounting Change [Abstract] Receivables: EBP, Receivable [Abstract] Plan's Assets at Fair Value EBP, Investment, Fair Value and NAV [Table Text Block] 2 EBP, Two Years [Member] EBP, Two Years 4 EBP, Four Years [Member] EBP, Four Years Investments [Domain] Investments [Domain] 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] Company EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash Income Taxes EBP, Income Taxes [Policy Text Block] EBP, Income Taxes Minimum Minimum [Member] Interest income on notes receivable from participants EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant Investment Type [Axis] Investment Type [Axis] Total contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution Participant 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 Interest and dividends from mutual funds 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] Origin Bancorp, Inc. (“Company”) stock EBP, Employer, Common Stock [Member] EBP, Schedule of Asset Held for Investment [Abstract] 1 EBP, One Year [Member] EBP, One Year EBP, Accounting Policy [Table] EBP, Accounting Policy [Table] Net investment income, interest income and contributions EBP, Change in Net Asset Available for Benefit, Increase Allowance for credit losses EBP, Note Receivable from Participant, Allowance for Credit Loss Investment income: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment [Abstract] Investment, Identifier [Axis] Investment, Identifier [Axis] Administrative expenses EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense EBP, Asset Held for Investment EBP, Asset Held for Investment Risks and Uncertainties EBP, Risk and Uncertainty [Policy Text Block] Document Information [Line Items] Document Information [Line Items] 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] 3 EBP, Three Years [Member] EBP, Three Years EBP, Requisite Service Period EBP, Requisite Service Period EBP, Requisite Service Period EBP, Tax Status [Table] EBP, Tax Status [Table] Net increase in net assets available for benefits EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Related Party and Party-in-Interest Transactions EBP, Related Party and Party-in-Interest Transactions [Text Block] EBP, Related Party and Party-in-Interest Transactions [Abstract] Excess contributions payable EBP, Excess Contribution Payable EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Total receivables EBP, Receivable Company contributions EBP, Employer Contribution, Receivable Automatic deferral rate EBP, Participant Contribution, Automatic, Deferral Rate Investments, at fair value: EBP, Investment, Fair Value [Abstract] Benefits paid to participants EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Dividends from Company stock Dividend income EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment Current value 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, Company Contributions Vesting Schedule EBP, Company Contributions Vesting Schedule [Table Text Block] EBP, Company Contributions Vesting Schedule Distributions in process EBP, Distributions In Process EBP, Distributions In Process EBP, Statement of Net Asset Available for Benefit [Abstract] EBP, Accounting Policy [Line Items] EBP, Accounting Policy [Line Items] EBP, Tax Status [Abstract] Automatic deferral rate, annual increase EBP, Participant Contribution, Automatic, Annual Increase Deferral Rate EBP, Participant Contribution, Automatic, Annual Increase Deferral Rate 5 or more EBP, Five Years Or More [Member] EBP, Five Years Or More Notes receivable from participants EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Investment Valuation and Income Recognition EBP, Investment [Policy Text Block] Participant contributions EBP, Participant Contribution, Receivable Document Type Document Type EBP, Vesting Period [Axis] EBP, Vesting Period, By Years Of Service [Axis] EBP, Vesting Period, By Years Of Service Entity Central Index Key Entity Central Index Key Note receivable from participants, interest rate EBP, Asset Held for Investment, Participant Loan, Interest Rate Profit-sharing contributions EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Profit-sharing EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Profit-sharing EBP, Tax Status [Line Items] EBP, Tax Status [Line Items] Deductions from net assets: EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Forfeited nonvested account, decrease from employer contribution EBP, Forfeited Nonvested Account, Decrease from Employer Contribution 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 Plan's Tax Status EBP, Tax Status [Text Block] Maximum borrowing, to total account, percentage EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage Document Information [Table] Document Information [Table] Notes Receivable from Participants EBP, Note Receivable from Participant [Policy Text Block] Net 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] Origin Bancorp, Inc. Common Stock, par value (in dollars per share) EBP, Investment, Par or Maturity Value Per Share EBP, Investment, Par or Maturity Value Per Share Level 3 Fair Value, Inputs, Level 3 [Member] Net assets available for benefits Beginning of year End of year EBP, Net Asset Available for Benefit Entity [Domain] Entity [Domain] Contributions: EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] Forfeited nonvested account EBP, Forfeited Nonvested Account Matching percentage EBP, Employer Contribution, Matching Percentage EBP, Investment, Fair Value and NAV [Table] EBP, Investment, Fair Value and NAV [Table] Note receivable from participants, maturity term EBP, Note Receivable From Participant, Borrowing Term EBP, Note Receivable From Participant, Borrowing Term EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Line Items]