Regulatory Matters - Capital and Risk-Based Capital and Leverage Ratios (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Renasant Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital to average assets (leverage) - amount	$ 1,252,116	$ 1,188,412
Tier 1 capital to average assets (leverage) - ratio	10.56%	10.11%
Common equity tier 1 capital to risk-weighted assets - amount	$ 1,147,024	$ 1,085,751
Common equity tier 1 capital to risk-weighted assets - ratio	11.36%	11.05%
Tier 1 capital to risk-weighted assets - amount	$ 1,252,116	$ 1,188,412
Tier 1 capital to risk-weighted assets - ratio	12.40%	12.10%
Total capital to risk-weighted assets - amount	$ 1,421,600	$ 1,386,507
Total capital to risk-weighted assets - ratio	14.07%	14.12%
Renasant Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital to average assets (leverage) - amount	$ 1,326,065	$ 1,276,976
Tier 1 capital to average assets (leverage) - ratio	11.20%	10.88%
Common equity tier 1 capital to risk-weighted assets - amount	$ 1,326,065	$ 1,276,976
Common equity tier 1 capital to risk-weighted assets - ratio	13.15%	13.02%
Tier 1 capital to risk-weighted assets - amount	$ 1,326,065	$ 1,276,976
Tier 1 capital to risk-weighted assets - ratio	13.15%	13.02%
Total capital to risk-weighted assets - amount	$ 1,381,973	$ 1,331,619
Total capital to risk-weighted assets - ratio	13.70%	13.58%