Fair Value Measurement of Assets and Liabilities - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Financial assets
Interest bearing deposits with banks	$ 1,478,713	$ 607,135
Equity securities	71,513	64,464
Investment securities held to maturity	3,028,284	3,302,312
Net loans	8,800
Accrued interest receivable	239,941	245,498
Financial liabilities
Deposits with stated maturities	12,342,544	13,176,724
U.S. Treasury securities
Financial assets
Investment securities held to maturity	25,461	25,978
U.S. government agency securities
Financial assets
Investment securities held to maturity	252,302	261,555
Obligations of states and political subdivisions
Financial assets
Investment securities held to maturity	346,361	387,527
Residential mortgage-backed securities
Financial assets
Investment securities held to maturity	2,292,148	2,521,926
Trust preferred securities
Financial assets
Investment securities held to maturity	29,145	30,650
Corporate and other debt securities
Financial assets
Investment securities held to maturity	82,867	74,676
Carrying Amount
Financial assets
Investment securities held to maturity	3,532,220	3,740,413
Carrying Amount | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets
Cash and due from banks	411,412	284,090
Interest bearing deposits with banks	1,478,713	607,135
Accrued interest receivable	239,941	245,498
Financial liabilities
Deposits without stated maturities	37,733,313	36,066,105
Accrued interest payable	150,564	159,496
Carrying Amount | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury securities
Financial assets
Investment securities held to maturity	25,480	26,232
Carrying Amount | Significant Other Observable  Inputs (Level 2)
Financial assets
Federal Reserve Bank and Federal Home Loan Bank stock	328,497	320,727
Financial liabilities
Deposits with stated maturities	12,342,544	13,176,724
Short-term borrowings	72,718	917,834
Long-term borrowings	3,174,155	2,328,375
Junior subordinated debentures issued to capital trusts	57,455	57,108
Carrying Amount | Significant Other Observable  Inputs (Level 2) | U.S. government agency securities
Financial assets
Investment securities held to maturity	301,315	305,996
Carrying Amount | Significant Other Observable  Inputs (Level 2) | Obligations of states and political subdivisions
Financial assets
Investment securities held to maturity	372,489	405,470
Carrying Amount | Significant Other Observable  Inputs (Level 2) | Residential mortgage-backed securities
Financial assets
Investment securities held to maturity	2,710,642	2,885,303
Carrying Amount | Significant Other Observable  Inputs (Level 2) | Trust preferred securities
Financial assets
Investment securities held to maturity	36,081	37,062
Carrying Amount | Significant Other Observable  Inputs (Level 2) | Corporate and other debt securities
Financial assets
Investment securities held to maturity	86,213	80,350
Carrying Amount | Significant Unobservable Inputs (Level 3)
Financial assets
Equity securities	36,871	29,031
Net loans	48,240,861	49,764,215
Fair Value
Financial assets
Investment securities held to maturity	3,028,284	3,302,312
Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets
Cash and due from banks	411,412	284,090
Interest bearing deposits with banks	1,478,713	607,135
Accrued interest receivable	239,941	245,498
Financial liabilities
Deposits without stated maturities	37,733,313	36,066,105
Accrued interest payable	150,564	159,496
Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury securities
Financial assets
Investment securities held to maturity	25,461	25,978
Fair Value | Significant Other Observable  Inputs (Level 2)
Financial assets
Federal Reserve Bank and Federal Home Loan Bank stock	328,497	320,727
Financial liabilities
Deposits with stated maturities	12,363,365	13,103,381
Short-term borrowings	68,032	901,617
Long-term borrowings	3,109,622	2,256,997
Junior subordinated debentures issued to capital trusts	54,957	47,374
Fair Value | Significant Other Observable  Inputs (Level 2) | U.S. government agency securities
Financial assets
Investment securities held to maturity	252,302	261,555
Fair Value | Significant Other Observable  Inputs (Level 2) | Obligations of states and political subdivisions
Financial assets
Investment securities held to maturity	346,361	387,527
Fair Value | Significant Other Observable  Inputs (Level 2) | Residential mortgage-backed securities
Financial assets
Investment securities held to maturity	2,292,148	2,521,926
Fair Value | Significant Other Observable  Inputs (Level 2) | Trust preferred securities
Financial assets
Investment securities held to maturity	29,145	30,650
Fair Value | Significant Other Observable  Inputs (Level 2) | Corporate and other debt securities
Financial assets
Investment securities held to maturity	82,867	74,676
Fair Value | Significant Unobservable Inputs (Level 3)
Financial assets
Equity securities	36,871	29,031
Net loans	$ 46,634,654	$ 47,981,499