Capital and Regulatory Matters - Actual Capital Amounts and Ratios (Details) $ in Thousands	Sep. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)
Origin Bancorp, Inc.
Common Equity Tier 1 Capital to Risk-Weighted Assets
Actual, amount	$ 1,113,214	$ 1,085,860
Actual, ratio	0.1359	0.1332
Minimum capital required, amount	$ 573,421	$ 570,647
Minimum capital required, ratio	0.0700	0.0700
Tier 1 Capital to Risk-Weighted Assets
Actual, amount	$ 1,129,191	$ 1,101,766
Actual, ratio	0.1379	0.1352
Minimum capital required, amount	$ 696,192	$ 692,929
Minimum capital required, ratio	0.0850	0.0850
Total Capital to Risk-Weighted Assets
Actual, amount	$ 1,302,509	$ 1,339,735
Actual, ratio	0.1590	0.1644
Minimum capital required, amount	$ 860,131	$ 855,670
Minimum capital required, ratio	0.1050	0.1050
Leverage Ratio
Actual, amount	$ 1,129,191	$ 1,101,766
Actual, ratio	0.1169	0.1108
Minimum capital required, amount	$ 386,283	$ 397,635
Minimum capital required, ratio	0.0400	0.0400
Origin Bank \| Origin Bank
Common Equity Tier 1 Capital to Risk-Weighted Assets
Actual, amount	$ 1,050,761	$ 1,075,768
Actual, ratio	0.1293	0.1329
Minimum capital required, amount	$ 568,888	$ 566,620
Minimum capital required, ratio	0.0700	0.0700
Well capitalized, amount	$ 528,253	$ 526,147
Well capitalized, ratio	6.50%	6.50%
Tier 1 Capital to Risk-Weighted Assets
Actual, amount	$ 1,050,761	$ 1,075,768
Actual, ratio	0.1293	0.1329
Minimum capital required, amount	$ 690,793	$ 688,038
Minimum capital required, ratio	0.0850	0.0850
To be well capitalized under prompt corrective action provisions, amount	$ 650,158	$ 647,565
To be well capitalized under prompt corrective action provisions, ratio	0.0800	0.0800
Total Capital to Risk-Weighted Assets
Actual, amount	$ 1,150,884	$ 1,239,644
Actual, ratio	0.1416	0.1531
Minimum capital required, amount	$ 853,331	$ 850,353
Minimum capital required, ratio	0.1050	0.1050
To be well capitalized under prompt corrective action provisions, amount	$ 812,697	$ 809,860
To be well capitalized under prompt corrective action provisions, ratio	0.1000	0.1000
Leverage Ratio
Actual, amount	$ 1,050,761	$ 1,075,768
Actual, ratio	0.1097	0.1089
Minimum capital required, amount	$ 383,154	$ 395,154
Minimum capital required, ratio	0.0400	0.0400
To be well capitalized under prompt corrective action provisions, amount	$ 478,942	$ 493,943
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

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

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