Regulatory Capital Requirements - Schedule of Regulatory Requirements (Details) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Red River Bank
Total Risk-Based Capital
Actual Amount	$ 305,771	$ 271,061
Actual Ratio (as a percent)	0.1706	0.1717
Regulatory Requirements, Minimum , Amount	$ 143,372	$ 126,307
Regulatory Requirements, Minimum, Ratio (as a percent)	0.0800	0.0800
Regulatory Requirements, Minimum Plus CCB, Amount	$ 188,176	$ 165,778
Regulatory Requirements, Minimum Plus CCB, Ratio (as a percent)	0.1050	0.1050
Tier I Risk-Based Capital
Actual Amount	$ 286,595	$ 253,110
Actual Ratio (as a percent)	0.1599	0.1603
Regulatory Requirements, Minimum, Amount	$ 107,529	$ 94,731
Regulatory Requirements, Minimum, Ratio (as a percent)	0.0600	0.0600
Regulatory Requirements, Minimum Plus CCB, Amount	$ 152,333	$ 134,202
Regulatory Requirements, Minimum Plus CCB, Ratio (as a percent)	0.0850	0.0850
Common Equity Tier I Capital
Actual Amount	$ 286,595	$ 253,110
Actual Ratio (as a percent)	0.1599	0.1603
Regulatory Requirements, Minimum, Amount	$ 80,647	$ 71,048
Regulatory Requirements, Minimum, Ratio (as a percent)	0.0450	0.0450
Regulatory Requirements, Minimum Plus CCB, Amount	$ 125,451	$ 110,519
Regulatory Requirements, Minimum Plus CCB, Ratio (as a percent)	0.0700	0.0700
Tier I Leverage Capital
Actual Amount	$ 286,595	$ 253,110
Actual Ratio (as a percent)	0.0923	0.0998
Regulatory Requirements, Minimum, Amount	$ 124,241	$ 101,495
Regulatory Requirements, Minimum, Ratio (as a percent)	0.0400	0.0400
Regulatory Requirements, Minimum Plus CCB, Amount	$ 124,241	$ 101,495
Regulatory Requirements, Minimum Plus CCB, Ratio (as a percent)	0.0400	0.0400
Red River Bancshares, Inc.
Total Risk-Based Capital
Actual Amount	$ 319,553	$ 294,962
Actual Ratio (as a percent)	0.1783	0.1868
Tier I Risk-Based Capital
Actual Amount	$ 300,377	$ 277,011
Actual Ratio (as a percent)	0.1676	0.1755
Common Equity Tier I Capital
Actual Amount	$ 300,377	$ 277,011
Actual Ratio (as a percent)	0.1676	0.1755
Tier I Leverage Capital
Actual Amount	$ 300,377	$ 277,011
Actual Ratio (as a percent)	0.0967	0.1092