Investment Securities - Amortized Cost of Held to Maturity Debt Securities by External Credit Rating (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	$ 3,740,413	$ 3,828,984
U.S. Treasury securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	26,232	66,911
U.S. government agency securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	305,996	260,392
Obligations of states and state agencies
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	88,556	99,238
Municipal bonds
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	316,914	381,060
Obligations of states and political subdivisions
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	405,470	480,298
Residential mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	2,885,303	2,909,106
Trust preferred securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	37,062	37,043
Corporate and other debt securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	80,350	75,234
AAA/AA/A Rated
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	3,567,474	3,646,840
AAA/AA/A Rated | U.S. Treasury securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	26,232	66,911
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	305,996	260,392
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	66,502	74,943
AAA/AA/A Rated | Municipal bonds
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	283,441	333,488
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	349,943	408,431
AAA/AA/A Rated | Residential mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	2,885,303	2,909,106
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	2,000
BBB rated
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	6,000	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	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	6,000	6,000
Non-investment grade rated
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	5,330	5,497
Non-investment grade rated | U.S. Treasury securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
Non-investment grade 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-investment grade rated | Obligations of states and state agencies
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	5,330	5,497
Non-investment grade rated | Municipal bonds
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
Non-investment grade rated | Obligations of states and political subdivisions
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	5,330	5,497
Non-investment grade rated | Residential mortgage-backed securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
Non-investment grade rated | Trust preferred securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
Non-investment grade rated | Corporate and other debt securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	0
Non-rated
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	161,609	170,647
Non-rated | U.S. Treasury securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	0	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	16,724	18,798
Non-rated | Municipal bonds
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	33,473	47,572
Non-rated | Obligations of states and political subdivisions
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	50,197	66,370
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	37,062	37,043
Non-rated | Corporate and other debt securities
Schedule of Held-to-Maturity Securities [Line Items]
Amortized cost of held to maturity debt securities	$ 74,350	$ 67,234