Regulatory Matters - Capital and Risk-Based Capital and Leverage Ratios (Details) $ in Thousands	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Renasant corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Capital to Average Assets (Leverage) - Amount	$ 1,395,321	$ 1,306,597
Tier 1 Capital to Average Assets (Leverage) - Ratio	0.0918	0.0937
Common Equity Tier 1 Capital to Risk-Weighted Assets - Amount	$ 1,287,684	$ 1,199,394
Common Equity Tier 1 Capital to Risk-Weighted Assets - Ratio	11.02%	10.93%
Tier 1 Capital to Risk-Weighted Assets - Amount	$ 1,395,321	$ 1,306,597
Tier 1 Capital to Risk-Weighted Assets - Ratio	0.1194	0.1191
Total Capital to Risk-Weighted Assets - Amount	$ 1,712,500	$ 1,653,694
Total Capital to Risk-Weighted Assets - Ratio	0.1466	0.1507
Renasant bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Capital to Average Assets (Leverage) - Amount	$ 1,454,879	$ 1,369,994
Tier 1 Capital to Average Assets (Leverage) - Ratio	0.0958	0.0983
Common Equity Tier 1 Capital to Risk-Weighted Assets - Amount	$ 1,454,879	$ 1,369,994
Common Equity Tier 1 Capital to Risk-Weighted Assets - Ratio	12.45%	12.49%
Tier 1 Capital to Risk-Weighted Assets - Amount	$ 1,454,879	$ 1,369,994
Tier 1 Capital to Risk-Weighted Assets - Ratio	0.1245	0.1249
Total Capital to Risk-Weighted Assets - Amount	$ 1,574,697	$ 1,504,985
Total Capital to Risk-Weighted Assets - Ratio	0.1348	0.1373