CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income, before-tax amount	$ 221,745	$ 227,915	$ 481,616	$ 441,646
Net income, tax	(47,801)	(49,863)	(105,513)	(92,558)
Net income	173,944	178,052	376,103	349,088
Before-tax Amount
Net unrealized gains (losses) arising during the period	(109,525)	(429,408)	43,556	(1,050,890)
Reclassification adjustment for realized (gains) losses included in net income	0	0	(1,030)	0
Net change	(109,525)	(429,408)	42,526	(1,050,890)
Income Tax
Net unrealized gains (losses) arising during the period	26,659	102,328	(10,601)	249,351
Reclassification adjustment for realized (gains) losses included in net income	0	0	251	0
Net change	26,659	102,328	(10,350)	249,351
Net of Tax Amount
Net unrealized gains (losses) arising during the period	(82,866)	(327,080)	32,955	(801,539)
Reclassification adjustment for realized (gains) losses included in net income	0	0	(779)	0
Net change	(82,866)	(327,080)	32,176	(801,539)
Before-tax Amount
Net unrealized gains (losses) arising during the period	(73,123)	(48,332)	(63,123)	(184,310)
Reclassification adjustment for realized (gains) losses included in net income	42,748	(978)	82,640	(3,167)
Net change	(30,375)	(49,310)	19,517	(187,477)
Income Tax
Net unrealized gains (losses) arising during the period	17,798	11,517	15,364	43,878
Reclassification adjustment for realized (gains) losses included in net income	(10,405)	233	(20,115)	754
Net change	7,393	11,750	(4,751)	44,632
Net of Tax Amount
Net unrealized gains (losses) arising during the period	(55,325)	(36,815)	(47,759)	(140,432)
Reclassification adjustment for realized (gains) losses included in net income	32,343	(745)	62,525	(2,413)
Net change	(22,982)	(37,560)	14,766	(142,845)
Total other comprehensive income (loss)	(139,900)	(478,718)	62,043	(1,238,367)
Total other comprehensive income (loss), income tax	34,052	114,078	(15,101)	293,983
Total other comprehensive income (loss), net of tax	(105,848)	(364,640)	46,942	(944,384)
Comprehensive income (loss)	68,096	(186,588)	423,045	(595,296)
Less: comprehensive income (loss) attributable to noncontrolling interest	(166)	0	(166)	0
Comprehensive income (loss) attributable to Synovus Financial Corp.	$ 68,262	$ (186,588)	$ 423,211	$ (595,296)