Renasant Corporation (Parent Company Only) Condensed Financial Information - Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income	$ 44,420	$ 31,964	$ 36,710	$ 33,826	$ 16,511	$ 26,421	$ 25,284	$ 23,972	$ 146,920	$ 92,188	$ 90,930
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of securities									16	(148)	(1,186)
Decrease (increase) in other assets									44,044	(6,620)	10,136
(Decrease) increase in other liabilities									(41,954)	(12,572)	(16,694)
Net cash provided by operating activities									77,406	201,561	163,797
Investing activities
Net cash (paid) received in acquisition									153,502	41,685	25,263
Net cash (used in) provided by investing activities									(498,581)	75,142	(351,993)
Financing activities
Cash paid for dividends									(43,614)	(34,416)	(29,734)
Cash received on exercise of stock-based compensation									201	173	415
Excess tax benefits from exercise of stock options									0	0	2,771
Repurchase of shares in connection with stock repurchase program									(7,062)	0	0
Repayment of long-term debt									(849)	(170,240)	(47,230)
Proceeds from issuance of long-term debt									0	0	98,385
Proceeds from equity offering									0	0	84,105
Net cash provided by (used in) financing activities									708,833	(301,474)	282,849
Net increase (decrease) in cash and cash equivalents									287,658	(24,771)	94,653
Cash and cash equivalents at beginning of year				281,453				306,224	281,453	306,224	211,571
Cash and cash equivalents at end of year	569,111				281,453				569,111	281,453	306,224
Renasant Corporation
Operating activities
Net income									146,920	92,188	90,930
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of securities									0	0	(1,186)
Equity in undistributed net income of bank subsidiary									(103,619)	(65,970)	(65,591)
Amortization/depreciation/accretion									160	656	560
Decrease (increase) in other assets									3,381	(1,069)	(556)
(Decrease) increase in other liabilities									(171)	(2,291)	564
Net cash provided by operating activities									46,671	23,514	24,721
Investing activities
Purchases of securities held to maturity and available for sale									0	0	(1,380)
Sales and maturities of securities held to maturity and available for sale									1,052	1,555	6,101
Investment in subsidiaries									0	(25,000)	(75,000)
Net cash (paid) received in acquisition									(34,836)	4,834	0
Other investing activities									423	(54)	0
Net cash (used in) provided by investing activities									(33,361)	(18,665)	(70,279)
Financing activities
Cash paid for dividends									(43,614)	(34,416)	(29,734)
Cash received on exercise of stock-based compensation									201	173	415
Excess tax benefits from exercise of stock options									0	0	2,771
Repurchase of shares in connection with stock repurchase program									(7,062)	0	0
Repayment of long-term debt									0	(10,310)	0
Proceeds from issuance of long-term debt									0	0	98,127
Proceeds from equity offering									0	0	84,105
Other financing activities									(93)	310	0
Net cash provided by (used in) financing activities									(50,568)	(44,243)	155,684
Net increase (decrease) in cash and cash equivalents									(37,258)	(39,394)	110,126
Cash and cash equivalents at beginning of year				$ 81,839				$ 121,233	81,839	121,233	11,107
Cash and cash equivalents at end of year	$ 44,581				$ 81,839				$ 44,581	$ 81,839	$ 121,233