Condensed Financial Information Of Synovus Financial Corp. (Parent Company Only) (Condensed Statements of Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Net income, Before-tax Amount									$ 388,451	$ 358,573	$ 302,559
Net income, Tax (Expense) Benefit	$ (39,519)	$ (37,375)	$ (33,574)	$ (31,199)	$ (32,342)	$ (36,058)	$ (32,242)	$ (31,849)	(141,667)	(132,491)	(107,310)
Net income	$ 68,549	$ 65,245	$ 60,457	$ 52,531	$ 58,398	$ 57,928	$ 55,792	$ 53,963	246,784	226,082	195,249
Reclassification adjustment for losses realized in net income, Before-tax Amount									467	521	448
Reclassification adjustment for losses realized in net income, Tax (Expense) Benefit									(180)	(201)	(173)
Reclassification adjustment for losses realized in net income, Net of Tax Amount									287	320	275
Reclassification adjustment for net gains realized in net income on investment securities available for sale, Before-tax Amount									(6,011)	(2,769)	(1,331)
Reclassification adjustment for net gains realized in net income on investment securities available for sale, Tax (Expense) Benefit									2,314	1,066	513
Reclassification adjustment for net gains realized in net income on investment securities available for sale, Net of Tax Amount									(3,697)	(1,703)	(818)
Net unrealized (losses) gains arising during the period, Before-tax Amount									(36,432)	(25,707)	47,223
Net unrealized (losses) gains arising during the period, Tax (Expense) Benefit									14,027	9,901	(18,182)
Net unrealized (losses) gains arising during the period, Net of Tax Amount									(22,405)	(15,806)	29,041
Other comprehensive (loss) income, Before-tax Amount									(42,018)	(27,991)	46,591
Other comprehensive (loss) income, Tax (Expense) Benefit									16,178	10,777	(17,938)
Other comprehensive (loss) income, Net of Tax Amount									(25,840)	(17,214)	28,653
Comprehensive income, Net of Tax Amount									220,944	208,868	223,902
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net income, Before-tax Amount									388,451	358,573	302,559
Net income, Tax (Expense) Benefit									(141,667)	(132,491)	(107,310)
Net income									246,784	226,082	195,249
Reclassification adjustment for losses realized in net income, Before-tax Amount									467	521	448
Reclassification adjustment for losses realized in net income, Tax (Expense) Benefit									(180)	(201)	(173)
Reclassification adjustment for losses realized in net income, Net of Tax Amount									287	320	275
Reclassification adjustment for net gains realized in net income on investment securities available for sale, Before-tax Amount									(5,763)	0	0
Reclassification adjustment for net gains realized in net income on investment securities available for sale, Tax (Expense) Benefit									2,219	0	0
Reclassification adjustment for net gains realized in net income on investment securities available for sale, Net of Tax Amount									(3,544)	0	0
Net unrealized (losses) gains arising during the period, Before-tax Amount									2,358	2,908	21
Net unrealized (losses) gains arising during the period, Tax (Expense) Benefit									(908)	(1,120)	(8)
Net unrealized (losses) gains arising during the period, Net of Tax Amount									1,450	1,788	13
Other comprehensive gain (loss) of bank subsidiary, Before-tax Amount									(39,080)	(31,420)	46,122
Other comprehensive gain (loss) of bank subsidiary, Tax (expense) Benefit									15,047	12,098	(17,757)
Other comprehensive gain (loss) of bank subsidiary, Net of Tax Amount									(24,033)	(19,322)	28,365
Other comprehensive (loss) income, Before-tax Amount									(42,018)	(27,991)	46,591
Other comprehensive (loss) income, Tax (Expense) Benefit									16,178	10,777	(17,938)
Other comprehensive (loss) income, Net of Tax Amount									(25,840)	(17,214)	28,653
Comprehensive income, Net of Tax Amount									$ 220,944	$ 208,868	$ 223,902