Investment Securities - Amortized Cost of Held to Maturity Debt Securities by External Credit Rating (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	$ 3,496,571	$ 3,532,220
U.S. Treasury securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities		25,480
U.S. government agency securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	292,269	301,315
Obligations of states and state agencies
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	60,801	68,025
Municipal bonds
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	293,074	304,464
Obligations of states and political subdivisions
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	353,875	372,489
Residential mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	2,732,752	2,710,642
Trust preferred securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	36,103	36,081
Corporate and other debt securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	81,572	86,213
AAA/AA/A Rated
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	3,312,384	3,368,128
AAA/AA/A Rated \| U.S. Treasury securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities		25,480
AAA/AA/A Rated \| U.S. government agency securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	292,269	301,315
AAA/AA/A Rated \| Obligations of states and state agencies
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	47,458	52,770
AAA/AA/A Rated \| Municipal bonds
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	239,905	277,921
AAA/AA/A Rated \| Obligations of states and political subdivisions
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	287,363	330,691
AAA/AA/A Rated \| Residential mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	2,732,752	2,710,642
AAA/AA/A Rated \| Trust preferred securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0
AAA/AA/A Rated \| Corporate and other debt securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
BBB rated
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	3,000	6,000
BBB rated \| U.S. Treasury securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities		0
BBB rated \| U.S. government agency securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
BBB rated \| Obligations of states and state agencies
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
BBB rated \| Municipal bonds
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
BBB rated \| Obligations of states and political subdivisions
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
BBB rated \| Residential mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
BBB rated \| Trust preferred securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
BBB rated \| Corporate and other debt securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	3,000	6,000
Non-rated
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	181,187	158,092
Non-rated \| U.S. Treasury securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities		0
Non-rated \| U.S. government agency securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
Non-rated \| Obligations of states and state agencies
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	13,343	15,255
Non-rated \| Municipal bonds
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	53,169	26,543
Non-rated \| Obligations of states and political subdivisions
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	66,512	41,798
Non-rated \| Residential mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
Non-rated \| Trust preferred securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	36,103	36,081
Non-rated \| Corporate and other debt securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	$ 78,572	$ 80,213