Condensed Financial Information of Synovus Financial Corp. (Parent Company only) - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
ASSETS
Total cash, cash equivalents, and restricted cash	$ 2,451,426	$ 1,977,780	$ 3,009,853	$ 4,252,917
Other assets	2,587,324	2,471,638
Total assets	59,809,534	59,731,378
Liabilities and Shareholders' Equity
Long-term debt	1,932,534	4,109,597
Other liabilities	1,801,097	1,524,449
Total liabilities	54,665,386	55,255,577
Shareholders’ equity:
Preferred stock	537,145	537,145
Common stock	171,360	170,141
Additional paid-in capital	3,955,819	3,920,346
Accumulated other comprehensive income (loss), net	(1,117,073)	(1,442,117)
Retained earnings	2,517,226	2,234,770
Total Synovus Financial Corp. shareholders’ equity	5,119,993	4,475,801
Total liabilities and shareholders' equity	59,809,534	59,731,378
Parent Company
ASSETS
Cash due from bank subsidiary	573,761	517,235
Funds due from other depository institutions	4,839	7,250
Total cash, cash equivalents, and restricted cash	578,600	524,485	$ 398,348	$ 448,629
Investment in consolidated bank subsidiary, at equity	4,947,888	4,471,207
Investment in consolidated nonbank subsidiaries, at equity	114,932	92,349
Note receivable from bank subsidiary	100,000	100,000
Other assets	25,943	19,431
Total assets	5,767,363	5,207,472
Liabilities and Shareholders' Equity
Long-term debt	552,703	644,490
Other liabilities	94,667	87,181
Total liabilities	647,370	731,671
Shareholders’ equity:
Preferred stock	537,145	537,145
Common stock	171,360	170,141
Additional paid-in capital	3,955,819	3,920,346
Treasury stock	(944,484)	(944,484)
Accumulated other comprehensive income (loss), net	(1,117,073)	(1,442,117)
Retained earnings	2,517,226	2,234,770
Total Synovus Financial Corp. shareholders’ equity	5,119,993	4,475,801
Total liabilities and shareholders' equity	$ 5,767,363	$ 5,207,472