Regulatory Matters - Capital and Risk-Based Capital and Leverage Ratios (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Renasant Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital to average assets (leverage) - amount	$ 1,034,498	$ 979,604
Tier 1 capital to average assets (leverage) - ratio	10.63%	10.18%
Common equity tier 1 capital to risk-weighted assets - amount	$ 951,490	$ 896,733
Common equity tier 1 capital to risk-weighted assets - ratio	11.71%	11.34%
Tier 1 capital to risk-weighted assets - amount	$ 1,034,498	$ 979,604
Tier 1 capital to risk-weighted assets - ratio	12.73%	12.39%
Total capital to risk-weighted assets - amount	$ 1,198,046	$ 1,142,926
Total capital to risk-weighted assets - ratio	14.75%	14.46%
Renasant Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital to average assets (leverage) - amount	$ 1,057,998	$ 1,000,715
Tier 1 capital to average assets (leverage) - ratio	10.89%	10.42%
Common equity tier 1 capital to risk-weighted assets - amount	$ 1,057,998	$ 1,000,715
Common equity tier 1 capital to risk-weighted assets - ratio	13.04%	12.69%
Tier 1 capital to risk-weighted assets - amount	$ 1,057,998	$ 1,000,715
Tier 1 capital to risk-weighted assets - ratio	13.04%	12.69%
Total capital to risk-weighted assets - amount	$ 1,108,178	$ 1,050,751
Total capital to risk-weighted assets - ratio	13.66%	13.32%