Condensed Financial Information Of Synovus Financial Corp. (Parent Company Only) (Condensed Statements Of Income) (Details) - 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
Expenses
Interest expense									$ 139,188	$ 123,623	$ 118,644
Other expenses									821,313	755,923	717,655
Income before income taxes	$ 103,966	$ 152,675	$ 117,791	$ 105,704	$ 108,068	$ 102,620	$ 94,031	$ 83,730	480,138	388,451	358,573
Dividends on preferred stock									10,238	10,238	10,238
Net income available to common shareholders	$ 27,046	$ 95,448	$ 73,444	$ 69,298	$ 65,990	$ 62,686	$ 57,898	$ 49,972	265,236	236,546	215,844
Parent Company
Income
Cash dividends received from subsidiaries(1)									283,210	325,000	199,904
Cash distributions received from Synovus Bank									167,790	0	25,096
Interest income									1,443	2,565	8,865
Other income									345	4,595	(337)
Total income									452,788	332,160	233,528
Expenses
Interest expense									43,922	52,831	46,585
Other expenses									33,955	20,652	10,516
Total expenses									77,877	73,483	57,101
Income before income taxes									374,911	258,677	176,427
Allocated income tax benefit									(30,421)	(25,628)	(18,808)
Income before equity in undistributed (loss) income of subsidiaries									405,332	284,305	195,235
Equity in undistributed (loss) income of subsidiaries									(129,858)	(37,521)	30,847
Net income (loss) available to controlling interest									275,474	246,784	226,082
Dividends on preferred stock									10,238	10,238	10,238
Net income available to common shareholders									$ 265,236	$ 236,546	$ 215,844