Renasant Corporation (Parent Company Only) Condensed Financial Information (Details 2) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net income	$ 16,511	$ 26,421	$ 25,284	$ 23,972	$ 23,635	$ 23,179	$ 22,900	$ 21,216	$ 92,188	$ 90,930	$ 68,014
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of securities									(148)	(1,186)	(96)
Increase in other assets									(6,620)	10,136	9,463
(Decrease) increase in other liabilities									(12,572)	(16,694)	180
Net cash provided by operating activities									201,561	163,797	252,625
Investing activities
Net cash (paid) received in acquisition									41,685	25,263	24,776
Net cash provided by (used in) investing activities									75,142	(351,993)	(247,431)
Financing activities
Cash paid for dividends									(34,416)	(29,734)	(24,557)
Cash received on exercise of stock-based compensation									173	415	102
Excess tax benefits from exercise of stock options									0	2,771	537
Repayment of long-term debt									(170,240)	(47,230)	(308,766)
Proceeds from issuance of long-term debt									0	98,385	40
Proceeds from equity offering									0	84,105	0
Net cash (used in) provided by financing activities									(301,474)	282,849	44,794
Net (decrease) increase in cash and cash equivalents									(24,771)	94,653	49,988
Cash and cash equivalents at beginning of year				306,224				211,571	306,224	211,571	161,583
Cash and cash equivalents at end of year	281,453				306,224				281,453	306,224	211,571
Renasant Corporation
Operating activities
Net income									92,188	90,930	68,014
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of securities									0	(1,186)	0
Equity in undistributed net income of bank subsidiary									(65,970)	(65,591)	(47,428)
Amortization/depreciation/accretion									656	560	579
Increase in other assets									(1,069)	(556)	(1,377)
(Decrease) increase in other liabilities									(2,291)	564	1,088
Net cash provided by operating activities									23,514	24,721	20,876
Investing activities
Purchases of securities held to maturity and available for sale									0	(1,380)	(2,183)
Sales and maturities of securities held to maturity and available for sale									1,555	6,101	1,089
Investment in subsidiaries									(25,000)	(75,000)	0
Net cash (paid) received in acquisition									4,834	0	5,292
Other investing activities									(54)	0	0
Net cash provided by (used in) investing activities									(18,665)	(70,279)	4,198
Financing activities
Cash paid for dividends									(34,416)	(29,734)	(24,557)
Cash received on exercise of stock-based compensation									173	415	102
Excess tax benefits from exercise of stock options									0	2,771	520
Repayment of long-term debt									(10,310)	0	0
Repayments of advances from bank subsidiary									0	0	0
Proceeds from issuance of long-term debt									0	98,127	0
Proceeds from equity offering									0	84,105	0
Other financing activities									310	0	0
Net cash (used in) provided by financing activities									(44,243)	155,684	(23,935)
Net (decrease) increase in cash and cash equivalents									(39,394)	110,126	1,139
Cash and cash equivalents at beginning of year				$ 121,233				$ 11,107	121,233	11,107	9,968
Cash and cash equivalents at end of year	$ 81,839				$ 121,233				$ 81,839	$ 121,233	$ 11,107