Fair Value Measurement of Assets and Liabilities - Carrying Amounts and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financial assets
Interest bearing deposits with banks	$ 607,135	$ 503,622
Equity securities	64,464	48,731
Investment securities held to maturity	3,302,312	3,329,470
Accrued interest receivable	245,498	196,606
Financial liabilities
Deposits with stated maturities	13,176,724	9,556,457
U.S. Treasury securities
Financial assets
Investment securities held to maturity	25,978	65,889
U.S. government agency securities
Financial assets
Investment securities held to maturity	261,555	212,712
Obligations of states and political subdivisions
Financial assets
Investment securities held to maturity	387,527	453,195
Residential mortgage-backed securities
Financial assets
Investment securities held to maturity	2,521,926	2,495,797
Trust preferred securities
Financial assets
Investment securities held to maturity	30,650	31,106
Corporate and other debt securities
Financial assets
Investment securities held to maturity	74,676	70,771
Carrying Amount
Financial assets
Investment securities held to maturity	3,740,413	3,828,984
Carrying Amount | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets
Cash and due from banks	284,090	444,325
Interest bearing deposits with banks	607,135	503,622
Accrued interest receivable	245,498	196,606
Financial liabilities
Deposits without stated maturities	36,066,105	38,080,457
Accrued interest payable	159,496	45,617
Carrying Amount | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury securities
Financial assets
Investment securities held to maturity	26,232	66,911
Carrying Amount | Significant Other Observable  Inputs (Level 2)
Financial assets
Federal Reserve Bank and Federal Home Loan Bank stock	320,727	238,056
Financial liabilities
Deposits with stated maturities	13,176,724	9,556,457
Short-term borrowings	917,834	138,729
Long-term borrowings	2,328,375	1,543,058
Junior subordinated debentures issued to capital trusts	57,108	56,760
Carrying Amount | Significant Other Observable  Inputs (Level 2) | U.S. government agency securities
Financial assets
Investment securities held to maturity	305,996	260,392
Carrying Amount | Significant Other Observable  Inputs (Level 2) | Obligations of states and political subdivisions
Financial assets
Investment securities held to maturity	405,470	480,298
Carrying Amount | Significant Other Observable  Inputs (Level 2) | Residential mortgage-backed securities
Financial assets
Investment securities held to maturity	2,885,303	2,909,106
Carrying Amount | Significant Other Observable  Inputs (Level 2) | Trust preferred securities
Financial assets
Investment securities held to maturity	37,062	37,043
Carrying Amount | Significant Other Observable  Inputs (Level 2) | Corporate and other debt securities
Financial assets
Investment securities held to maturity	80,350	75,234
Carrying Amount | Significant Unobservable Inputs (Level 3)
Financial assets
Equity securities	29,031	15,138
Net loans	49,764,215	46,458,545
Fair Value
Financial assets
Investment securities held to maturity	3,302,312	3,329,470
Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets
Cash and due from banks	284,090	444,325
Interest bearing deposits with banks	607,135	503,622
Accrued interest receivable	245,498	196,606
Financial liabilities
Deposits without stated maturities	36,066,105	38,080,457
Accrued interest payable	159,496	45,617
Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury securities
Financial assets
Investment securities held to maturity	25,978	65,889
Fair Value | Significant Other Observable  Inputs (Level 2)
Financial assets
Federal Reserve Bank and Federal Home Loan Bank stock	320,727	238,056
Financial liabilities
Deposits with stated maturities	13,103,381	9,443,253
Short-term borrowings	901,617	138,729
Long-term borrowings	2,256,997	1,395,991
Junior subordinated debentures issued to capital trusts	47,374	50,923
Fair Value | Significant Other Observable  Inputs (Level 2) | U.S. government agency securities
Financial assets
Investment securities held to maturity	261,555	212,712
Fair Value | Significant Other Observable  Inputs (Level 2) | Obligations of states and political subdivisions
Financial assets
Investment securities held to maturity	387,527	453,195
Fair Value | Significant Other Observable  Inputs (Level 2) | Residential mortgage-backed securities
Financial assets
Investment securities held to maturity	2,521,926	2,495,797
Fair Value | Significant Other Observable  Inputs (Level 2) | Trust preferred securities
Financial assets
Investment securities held to maturity	30,650	31,106
Fair Value | Significant Other Observable  Inputs (Level 2) | Corporate and other debt securities
Financial assets
Investment securities held to maturity	74,676	70,771
Fair Value | Significant Unobservable Inputs (Level 3)
Financial assets
Equity securities	29,031	15,138
Net loans	$ 47,981,499	$ 44,910,049