v3.26.1
Investment Securities - Amortized Cost of Debt Securities Held to Maturity by External Credit Rating (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities $ 3,757,944 $ 3,496,571
U.S. government agency securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 290,828 292,269
Obligations of states and state agencies    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 57,749 60,801
Municipal bonds    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 322,964 293,074
Obligations of states and political subdivisions    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 380,713 353,875
Residential mortgage-backed securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 2,973,477 2,732,752
Trust preferred securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 36,115 36,103
Corporate and other debt securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 76,811 81,572
AAA/AA/A Rated    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 3,540,152 3,312,384
AAA/AA/A Rated | U.S. government agency securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 290,828 292,269
AAA/AA/A Rated | Obligations of states and state agencies    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 44,905 47,458
AAA/AA/A Rated | Municipal bonds    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 230,942 239,905
AAA/AA/A Rated | Obligations of states and political subdivisions    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 275,847 287,363
AAA/AA/A Rated | Residential mortgage-backed securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 2,973,477 2,732,752
AAA/AA/A Rated | Trust preferred securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 0 0
AAA/AA/A Rated | Corporate and other debt securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 0 0
BBB rated    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 0 3,000
BBB rated | U.S. government agency securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 0 0
BBB rated | Obligations of states and state agencies    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 0 0
BBB rated | Municipal bonds    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 0 0
BBB rated | Obligations of states and political subdivisions    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 0 0
BBB rated | Residential mortgage-backed securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 0 0
BBB rated | Trust preferred securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 0 0
BBB rated | Corporate and other debt securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 0 3,000
Non-rated    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 217,792 181,187
Non-rated | U.S. government agency securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 0 0
Non-rated | Obligations of states and state agencies    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 12,844 13,343
Non-rated | Municipal bonds    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 92,022 53,169
Non-rated | Obligations of states and political subdivisions    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 104,866 66,512
Non-rated | Residential mortgage-backed securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 0 0
Non-rated | Trust preferred securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities 36,115 36,103
Non-rated | Corporate and other debt securities    
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]    
Amortized cost of held to maturity debt securities $ 76,811 $ 78,572