Regulatory Capital Requirements - Schedule of Regulatory Requirements (Details) $ in Thousands	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Red River Bank
Total Risk-Based Capital
Actual Amount	$ 333,797	$ 305,771
Actual Ratio (percent)	0.1657	0.1706
Regulatory Requirements, Minimum, Amount	$ 161,189	$ 143,372
Regulatory Requirements, Minimum, Ratio (percent)	0.0800	0.0800
Regulatory Requirements, Minimum Plus CCB, Amount	$ 211,560	$ 188,176
Regulatory Requirements, Minimum Plus CCB, Ratio (percent)	0.1050	0.1050
Tier I Risk-Based Capital
Actual Amount	$ 313,844	$ 286,595
Actual Ratio (percent)	0.1558	0.1599
Regulatory Requirements, Minimum, Amount	$ 120,892	$ 107,529
Regulatory Requirements, Minimum, Ratio (percent)	0.0600	0.0600
Regulatory Requirements, Minimum Plus CCB, Amount	$ 171,263	$ 152,333
Regulatory Requirements, Minimum Plus CCB, Ratio (percent)	0.0850	0.0850
Common Equity Tier I Capital
Actual Amount	$ 313,844	$ 286,595
Actual Ratio (percent)	0.1558	0.1599
Regulatory Requirements, Minimum, Amount	$ 90,669	$ 80,647
Regulatory Requirements, Minimum, Ratio (percent)	0.0450	0.0450
Regulatory Requirements, Minimum Plus CCB, Amount	$ 141,040	$ 125,451
Regulatory Requirements, Minimum Plus CCB, Ratio (percent)	0.0700	0.0700
Tier I Leverage Capital
Actual Amount	$ 313,844	$ 286,595
Actual Ratio (percent)	0.0994	0.0923
Regulatory Requirements, Minimum, Amount	$ 126,253	$ 124,241
Regulatory Requirements, Minimum, Ratio (percent)	0.0400	0.0400
Regulatory Requirements, Minimum Plus CCB, Amount	$ 126,253	$ 124,241
Regulatory Requirements, Minimum Plus CCB, Ratio (percent)	0.0400	0.0400
Red River Bancshares, Inc.
Total Risk-Based Capital
Actual Amount	$ 345,564	$ 319,553
Actual Ratio (percent)	0.1715	0.1783
Tier I Risk-Based Capital
Actual Amount	$ 325,611	$ 300,377
Actual Ratio (percent)	0.1616	0.1676
Common Equity Tier I Capital
Actual Amount	$ 325,611	$ 300,377
Actual Ratio (percent)	0.1616	0.1676
Tier I Leverage Capital
Actual Amount	$ 325,611	$ 300,377
Actual Ratio (percent)	0.1031	0.0967