Capital and Regulatory Matters - Actual Capital Amounts and Ratios (Details) $ in Thousands	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Origin Bancorp, Inc.
Common Equity Tier 1 Capital to Risk-Weighted Assets
Actual, amount	$ 1,073,318	$ 1,012,916
Actual, ratio	0.1246	0.1183
Minimum capital required, amount	$ 603,075	$ 599,455
Minimum capital required, ratio	0.0700	0.0700
Tier 1 Capital to Risk-Weighted Assets
Actual, amount	$ 1,089,200	$ 1,028,729
Actual, ratio	0.1264	0.1201
Minimum capital required, amount	$ 732,308	$ 727,907
Minimum capital required, ratio	0.0850	0.0850
Total Capital to Risk-Weighted Assets
Actual, amount	$ 1,331,311	$ 1,286,604
Actual, ratio	0.1545	0.1502
Minimum capital required, amount	$ 904,611	$ 899,184
Minimum capital required, ratio	0.1050	0.1050
Leverage Ratio
Actual, amount	$ 1,089,200	$ 1,028,729
Actual, ratio	0.1093	0.1050
Minimum capital required, amount	$ 398,551	$ 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	$ 1,064,953	$ 1,019,732
Actual, ratio	0.1243	0.1195
Minimum capital required, amount	$ 599,867	$ 597,548
Minimum capital required, ratio	0.0700	0.0700
Well capitalized, amount	$ 557,020	$ 554,866
Well capitalized, ratio	6.50%	6.50%
Tier 1 Capital to Risk-Weighted Assets
Actual, amount	$ 1,064,953	$ 1,019,732
Actual, ratio	0.1243	0.1195
Minimum capital required, amount	$ 728,410	$ 725,593
Minimum capital required, ratio	0.0850	0.0850
To be well capitalized under prompt corrective action provisions, amount	$ 685,563	$ 682,912
To be well capitalized under prompt corrective action provisions, ratio	0.0800	0.0800
Total Capital to Risk-Weighted Assets
Actual, amount	$ 1,233,004	$ 1,188,000
Actual, ratio	0.1439	0.1392
Minimum capital required, amount	$ 899,803	$ 896,320
Minimum capital required, ratio	0.1050	0.1050
To be well capitalized under prompt corrective action provisions, amount	$ 856,955	$ 853,638
To be well capitalized under prompt corrective action provisions, ratio	0.1000	0.1000
Leverage Ratio
Actual, amount	$ 1,064,953	$ 1,019,732
Actual, ratio	0.1075	0.1045
Minimum capital required, amount	$ 396,243	$ 390,246
Minimum capital required, ratio	0.0400	0.0400
To be well capitalized under prompt corrective action provisions, amount	$ 495,304	$ 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

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