Other Short-term Borrowings and Long-term Debt - Additional Information on Synovus' Short-term Borrowings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Debt Disclosure [Abstract]
Total balance at December 31,	$ 3,496	$ 603,384
Weighted average interest rate at December 31,	3.88%	4.51%
Maximum month-end balance during the year	$ 1,253,521	$ 1,705,069
Average amount outstanding during the year	$ 528,194	$ 466,254
Weighted average interest rate during the year	4.60%	2.32%