Capital and Regulatory Matters - Actual Capital Amounts and Ratios (Details) $ in Thousands	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Origin Bancorp, Inc.
Common Equity Tier 1 Capital to Risk-Weighted Assets
Actual, amount	$ 1,055,186	$ 1,012,916
Actual, ratio	0.1215	0.1183
Minimum capital required, amount	$ 608,166	$ 599,455
Minimum capital required, ratio	0.0700	0.0700
Tier 1 Capital to Risk-Weighted Assets
Actual, amount	$ 1,071,045	$ 1,028,729
Actual, ratio	0.1233	0.1201
Minimum capital required, amount	$ 738,484	$ 727,907
Minimum capital required, ratio	0.0850	0.0850
Total Capital to Risk-Weighted Assets
Actual, amount	$ 1,317,398	$ 1,286,604
Actual, ratio	0.1516	0.1502
Minimum capital required, amount	$ 912,247	$ 899,184
Minimum capital required, ratio	0.1050	0.1050
Leverage Ratio
Actual, amount	$ 1,071,045	$ 1,028,729
Actual, ratio	0.1070	0.1050
Minimum capital required, amount	$ 400,454	$ 391,822
Minimum capital required, ratio	0.0400	0.0400
Origin Bank \| Origin Bank
Common Equity Tier 1 Capital to Risk-Weighted Assets
Actual, amount	$ 1,049,556	$ 1,019,732
Actual, ratio	0.1216	0.1195
Minimum capital required, amount	$ 604,250	$ 597,548
Minimum capital required, ratio	0.0700	0.0700
Well capitalized, amount	$ 561,089	$ 554,866
Well capitalized, ratio	6.50%	6.50%
Tier 1 Capital to Risk-Weighted Assets
Actual, amount	$ 1,049,556	$ 1,019,732
Actual, ratio	0.1216	0.1195
Minimum capital required, amount	$ 733,732	$ 725,593
Minimum capital required, ratio	0.0850	0.0850
To be well capitalized under prompt corrective action provisions, amount	$ 690,571	$ 682,912
To be well capitalized under prompt corrective action provisions, ratio	0.0800	0.0800
Total Capital to Risk-Weighted Assets
Actual, amount	$ 1,221,862	$ 1,188,000
Actual, ratio	0.1415	0.1392
Minimum capital required, amount	$ 906,375	$ 896,320
Minimum capital required, ratio	0.1050	0.1050
To be well capitalized under prompt corrective action provisions, amount	$ 863,214	$ 853,638
To be well capitalized under prompt corrective action provisions, ratio	0.1000	0.1000
Leverage Ratio
Actual, amount	$ 1,049,556	$ 1,019,732
Actual, ratio	0.1053	0.1045
Minimum capital required, amount	$ 398,518	$ 390,246
Minimum capital required, ratio	0.0400	0.0400
To be well capitalized under prompt corrective action provisions, amount	$ 498,147	$ 487,807
To be well capitalized under prompt corrective action provisions, ratio	0.0500	0.0500

Common Equity Tier One Capital Required For Capital Adequacy To Risk Weighted Assets

No definition available.

Name:	obnk_CommonEquityTierOneCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	obnk_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Common Equity Tier One Capital Required to be Well Capitalized to Risk Weighted Assets

+ References

No definition available.

+ Details

Name:	obnk_CommonEquityTierOneCapitalRequiredtobeWellCapitalizedtoRiskWeightedAssets
Namespace Prefix:	obnk_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Tier One, Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets With Buffer

+ References

No definition available.

+ Details

Name:	obnk_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssetsWithBuffer
Namespace Prefix:	obnk_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Tier One, Risk Based Capital Required For Capital Adequacy With Buffer

+ References

No definition available.

+ Details

Name:	obnk_TierOneRiskBasedCapitalRequiredForCapitalAdequacyWithBuffer
Namespace Prefix:	obnk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of total capital as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_Capital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_CapitalAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of minimum total risk-based capital required for capital adequacy as defined by regulatory framework.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477270/942-505-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477270/942-505-50-1B

+ Details

Name:	us-gaap_CapitalRequiredForCapitalAdequacy
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum total risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum total risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_CapitalRequiredToBeWellCapitalized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum total risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of total risk-based capital to risk-weighted assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_CapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of Common Equity Tier 1 risk-based capital as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_CommonEquityTierOneCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_CommonEquityTierOneCapitalAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Ratio of Common Equity Tier 1 risk-based capital to risk-weighted assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_CommonEquityTierOneCapitalRatio
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum Common Equity Tier 1 risk-based capital required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_CommonEquityTierOneCapitalRequiredForCapitalAdequacy
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of minimum Common Equity Tier 1 risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_CommonEquityTierOneCapitalRequiredToBeWellCapitalized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of Tier 1 leverage capital as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_TierOneLeverageCapitalAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of minimum Tier 1 leverage capital required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacy
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum Tier 1 leverage capital to average assets required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum Tier 1 leverage capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum Tier 1 leverage capital to average assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of Tier 1 capital to average assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of Tier 1 risk-based capital as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of minimum Tier 1 risk-based capital required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacy
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum Tier 1 risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum Tier 1 risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum Tier 1 risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of Tier 1 risk-based capital to risk-weighted assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	srt_ConsolidatedEntitiesAxis=srt_ParentCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=srt_SubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=obnk_OriginBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: