Regulatory Matters - Capital and Risk-Based Capital and Leverage Ratios (Details) $ in Thousands	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Renasant corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital to average assets (leverage) - amount	$ 1,281,318	$ 1,262,588
Tier 1 capital to average assets (leverage) - ratio	0.0917	0.1037
Common equity tier 1 capital to risk-weighted assets - amount	$ 1,174,260	$ 1,156,828
Common equity tier 1 capital to risk-weighted assets - ratio	10.80%	11.12%
Tier 1 capital to risk-weighted assets - amount	$ 1,281,318	$ 1,262,588
Tier 1 capital to risk-weighted assets - ratio	0.1179	0.1214
Total capital to risk-weighted assets - amount	$ 1,618,837	$ 1,432,949
Total capital to risk-weighted assets - ratio	0.1489	0.1378
Renasant bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital to average assets (leverage) - amount	$ 1,344,938	$ 1,331,809
Tier 1 capital to average assets (leverage) - ratio	0.0964	0.1095
Common equity tier 1 capital to risk-weighted assets - amount	$ 1,344,938	$ 1,331,809
Common equity tier 1 capital to risk-weighted assets - ratio	12.38%	12.81%
Tier 1 capital to risk-weighted assets - amount	$ 1,344,938	$ 1,331,809
Tier 1 capital to risk-weighted assets - ratio	0.1238	0.1281
Total capital to risk-weighted assets - amount	$ 1,470,402	$ 1,388,553
Total capital to risk-weighted assets - ratio	0.1353	0.1336