CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income, before-tax amount	$ 124,194	$ 262,626	$ 605,810	$ 704,272
Net income, tax	(27,729)	(59,582)	(133,242)	(152,140)
Net income	96,465	203,044	472,568	552,132
Before-tax Amount
Net unrealized gains (losses) arising during the period	(384,866)	(565,121)	(341,310)	(1,616,011)
Reclassification adjustment for realized (gains) losses included in net income	0	0	(1,030)	0
Net change	(384,866)	(565,121)	(342,340)	(1,616,011)
Income Tax
Net unrealized gains (losses) arising during the period	93,676	134,668	83,075	384,019
Reclassification adjustment for realized (gains) losses included in net income	0	0	251	0
Net change	93,676	134,668	83,326	384,019
Net of Tax Amount
Net unrealized gains (losses) arising during the period	(291,190)	(430,453)	(258,235)	(1,231,992)
Reclassification adjustment for realized (gains) losses included in net income	0	0	(779)	0
Net change	(291,190)	(430,453)	(259,014)	(1,231,992)
Before-tax Amount
Net unrealized gains (losses) arising during the period	(39,096)	(111,549)	(102,218)	(284,216)
Reclassification adjustment for realized (gains) losses included in net income	48,296	10,253	130,935	(4,556)
Net change	9,200	(101,296)	28,717	(288,772)
Income Tax
Net unrealized gains (losses) arising during the period	9,516	26,582	24,880	67,685
Reclassification adjustment for realized (gains) losses included in net income	(11,755)	(2,442)	(31,870)	1,086
Net change	(2,239)	24,140	(6,990)	68,771
Net of Tax Amount
Net unrealized gains (losses) arising during the period	(29,580)	(84,967)	(77,338)	(216,531)
Reclassification adjustment for realized (gains) losses included in net income	36,541	7,811	99,065	(3,470)
Net change	6,961	(77,156)	21,727	(220,001)
Total other comprehensive income (loss)	(375,666)	(666,417)	(313,623)	(1,904,783)
Total other comprehensive income (loss), income tax	91,437	158,808	76,336	452,790
Total other comprehensive income (loss), net of tax amount	(284,229)	(507,609)	(237,287)	(1,451,993)
Comprehensive income (loss)	(187,764)	(304,565)	235,281	(899,861)
Less: comprehensive income (loss) attributable to noncontrolling interest	(630)	0	(796)	0
Comprehensive income (loss) attributable to Synovus Financial Corp.	$ (187,134)	$ (304,565)	$ 236,077	$ (899,861)