Regulatory Matters - Capital and Risk-Based Capital and Leverage Ratios (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Renasant Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital to average assets (leverage) - amount	$ 1,000,640	$ 979,604
Tier 1 capital to average assets (leverage) - ratio	10.61%	10.18%
Common equity tier 1 capital to risk-weighted assets - amount	$ 917,501	$ 896,733
Common equity tier 1 capital to risk-weighted assets - ratio	11.38%	11.34%
Tier 1 capital to risk-weighted assets - amount	$ 1,000,640	$ 979,604
Tier 1 capital to risk-weighted assets - ratio	12.41%	12.39%
Total capital to risk-weighted assets - amount	$ 1,164,193	$ 1,142,926
Total capital to risk-weighted assets - ratio	14.44%	14.46%
Renasant Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital to average assets (leverage) - amount	$ 1,023,486	$ 1,000,715
Tier 1 capital to average assets (leverage) - ratio	10.88%	10.42%
Common equity tier 1 capital to risk-weighted assets - amount	$ 1,023,486	$ 1,000,715
Common equity tier 1 capital to risk-weighted assets - ratio	12.71%	12.69%
Tier 1 capital to risk-weighted assets - amount	$ 1,023,486	$ 1,000,715
Tier 1 capital to risk-weighted assets - ratio	12.71%	12.69%
Total capital to risk-weighted assets - amount	$ 1,073,712	$ 1,050,751
Total capital to risk-weighted assets - ratio	13.33%	13.32%