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Other Short-term Borrowings and Long-term Debt - Schedule of Long-term Debt Instruments (Details) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2023 | Dec. 31, 2022
Debt Instrument [Line Items] |  |
Long-term debt | $ 1,932,534,000 | $ 4,109,597,000
Synovus Bank |  |
Debt Instrument [Line Items] |  |
Long-term debt | $ 1,379,831,000 | 3,465,107,000
4.00% Subordinated Notes, Due October 29, 2030 | Synovus Bank |  |
Debt Instrument [Line Items] |  |
Stated percentage | 4.00% |
Debt, face amount | $ 200,000,000.0 |
Interest rate period | 5 years |
Subordinated notes | $ 192,732,000 | $ 190,107,000
4.00% Subordinated Notes, Due October 29, 2030 | US Treasury Rate | Synovus Bank |  |
Debt Instrument [Line Items] |  |
Basis spread on variable rate | 3.625% |
Federal Home Loan Bank Advance | Synovus Bank |  |
Debt Instrument [Line Items] |  |
Weighted average interest rate | 5.57% | 4.56%
Other long-term debt | $ 700,000,000 | $ 3,275,000,000
Senior Notes | 5.625% Senior Bank Notes due February 15, 2028 | Synovus Bank |  |
Debt Instrument [Line Items] |  |
Stated percentage | 5.625% |
Debt, face amount | $ 500,000,000.0 |
Long-term debt, gross | 487,099,000 | 0
Parent Company |  |
Debt Instrument [Line Items] |  |
Long-term debt | $ 552,703,000 | 644,490,000
Parent Company | 5.90% Subordinated Notes, due February 7, 2029 |  |
Debt Instrument [Line Items] |  |
Stated percentage | 5.90% |
Debt, face amount | $ 300,000,000.0 |
Interest rate period | 5 years |
Subordinated notes | $ 201,925,000 | 298,158,000
Parent Company | 5.90% Subordinated Notes, due February 7, 2029 | Five-Year Mid Swap Rate |  |
Debt Instrument [Line Items] |  |
Basis spread on variable rate | 3.379% |
Parent Company | SOFR Plus Spread of 2.06% Debentures, due June 15, 2035 |  |
Debt Instrument [Line Items] |  |
Stated percentage | 2.06% |
Debt, face amount |  | $ 10,000,000
Interest rate at period end | 7.45% | 6.57%
Unsecured debt | $ 10,000,000 | $ 10,000,000
Parent Company | Senior Notes | 5.200% Senior Notes due August 11, 2025 |  |
Debt Instrument [Line Items] |  |
Stated percentage | 5.20% |
Debt, face amount | $ 350,000,000.0 |
Long-term debt, gross | $ 340,778,000 | $ 336,332,000

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