Regulatory Capital (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital conservation buffer	2.50%
CET1 capital
CET1 capital, actual	$ 5,206,521	$ 4,926,194
CET1 capital, For capital adequacy purposes	2,291,552	2,302,824
Tier 1 risk-based capital
Tier I risk-based capital, actual	5,743,666	5,463,339
Tier I risk-based capital, for capital adequacy purposes	3,055,403	3,070,432
Total risk-based capital
Total risk-based capital, actual	6,654,224	6,415,681
Total risk-based capital, for capital adequacy purposes	$ 4,073,871	$ 4,093,909
CET1 capital ratio
CET1 capital ratio, actual	10.22%	9.63%
CET1 capital ratio, for capital adequacy purposes	4.50%	4.50%
Tier 1 risk-based capital ratio
Tier I risk-based capital ratio, actual	0.1128	0.1068
Tier I risk-based capital ratio, for capital adequacy purposes	0.0600	0.0600
Total risk-based capital ratio
Total risk-based capital ratio, actual	0.1307	0.1254
Total risk-based capital ratio, for capital adequacy purposes	0.0800	0.0800
Leverage ratio
Leverage ratio, actual	0.0949	0.0907
Leverage ratio, for capital adequacy purposes	0.0400	0.0400
Synovus Bank
CET1 capital
CET1 capital, actual	$ 5,559,624	$ 5,446,703
CET1 capital, For capital adequacy purposes	2,288,092	2,300,126
CET1 capital, to be well capitalized under prompt corrective action provisions	3,305,022	3,322,404
Tier 1 risk-based capital
Tier I risk-based capital, actual	5,559,624	5,446,703
Tier I risk-based capital, for capital adequacy purposes	3,050,789	3,066,835
Tier I risk-based capital, to be well capitalized under prompt corrective action provisions	4,067,719	4,089,113
Total risk-based capital
Total risk-based capital, actual	6,249,947	6,079,152
Total risk-based capital, for capital adequacy purposes	4,067,719	4,089,113
Total risk-based capital, to be well capitalized under prompt corrective action provisions	$ 5,084,649	$ 5,111,391
CET1 capital ratio
CET1 capital ratio, actual	10.93%	10.66%
CET1 capital ratio, for capital adequacy purposes	4.50%	4.50%
CET1 capital ratio, to be well capitalized under prompt corrective action provisions	6.50%	6.50%
Tier 1 risk-based capital ratio
Tier I risk-based capital ratio, actual	0.1093	0.1066
Tier I risk-based capital ratio, for capital adequacy purposes	0.0600	0.0600
Tier I risk-based capital ratio, to be well capitalized under prompt corrective action provisions	0.0800	0.0800
Total risk-based capital ratio
Total risk-based capital ratio, actual	0.1229	0.1189
Total risk-based capital ratio, for capital adequacy purposes	0.0800	0.0800
Total risk-based capital ratio, to be well capitalized under prompt corrective action provisions	0.1000	0.1000
Leverage ratio
Leverage ratio, actual	0.0921	0.0906
Leverage ratio, for capital adequacy purposes	0.0400	0.0400
Leverage ratio, to be well capitalized under prompt corrective action provisions	0.0500	0.0500