Regulatory Matters - Capital and Risk-based Capital and Leverage Ratios (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Renasant Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount Included in Tier 1 Capital	$ 1,188,412	$ 979,604
Tier 1 Capital to Average Assets (Leverage) (percent)	10.11%	10.18%
Common Equity Tier One Capital to Risk - Weighted Assets, amount	$ 1,085,751	$ 896,733
Common Equity Tier One Capital to Risk - Weighted Assets (percent)	11.05%	11.34%
Tier 1 Capital to Risk -Weighted Assets, amount	$ 1,188,412	$ 979,604
Tier 1 Capital to Risk - Weighted Assets (percent)	12.10%	12.39%
Total Capital to Risk - Weighted Assets, amount	$ 1,386,507	$ 1,142,926
Total Capital to Risk - Weighted Assets (percent)	14.12%	14.46%
Renasant Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount Included in Tier 1 Capital	$ 1,276,976	$ 1,000,715
Tier 1 Capital to Average Assets (Leverage) (percent)	10.88%	10.42%
Common Equity Tier One Capital to Risk - Weighted Assets, amount	$ 1,276,976	$ 1,000,715
Common Equity Tier One Capital to Risk - Weighted Assets (percent)	13.02%	12.69%
Tier 1 Capital to Risk -Weighted Assets, amount	$ 1,276,976	$ 1,000,715
Tier 1 Capital to Risk - Weighted Assets (percent)	13.02%	12.69%
Total Capital to Risk - Weighted Assets, amount	$ 1,331,619	$ 1,050,751
Total Capital to Risk - Weighted Assets (percent)	13.58%	13.32%