Fair Value - Carrying Amounts and Estimated Fair Values of Financial Instruments, Not Carried at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, due from banks, money market,    and other interest-earning investments	$ 1,113,935	$ 728,412
Loans, net	31,523,663	30,819,970
Accrued interest receivable	188,988	190,521
Noninterest-bearing demand deposits	10,995,083	11,930,798
Time deposits	4,121,695	3,013,780
Federal funds purchased and interbank borrowings	618,955	581,489
Outstanding at period end	393,018	432,804	$ 509,275
Federal Home Loan Bank advances	4,981,612	3,829,018
Other borrowings	746,869	743,003
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. government-sponsored entities and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity		0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity		0
Quoted Prices in Active Markets for Identical Assets (Level 1) | States and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity		0
Significant Other Observable Inputs (Level 2) | U.S. government-sponsored entities and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity		656,358
Significant Other Observable Inputs (Level 2) | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity		982,963
Significant Other Observable Inputs (Level 2) | States and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity		1,004,361
Significant Unobservable Inputs (Level 3) | U.S. government-sponsored entities and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity		0
Significant Unobservable Inputs (Level 3) | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity		0
Significant Unobservable Inputs (Level 3) | States and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity		0
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, due from banks, money market,    and other interest-earning investments	1,113,935	728,412
Accrued interest receivable	188,988	190,521
Noninterest-bearing demand deposits	10,995,083	11,930,798
Checking, NOW, savings, and money market    interest-bearing deposits	19,801,014	20,056,252
Time deposits	4,121,695	3,013,780
Federal funds purchased and interbank borrowings	618,955	581,489
Outstanding at period end	393,018	432,804
Federal Home Loan Bank advances	4,981,612	3,829,018
Other borrowings	746,869	743,003
Accrued interest payable	28,792	19,547
Standby letters of credit	846	755
Commitments to extend credit	0	0
Carrying Value | U.S. government-sponsored entities and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	820,849	819,168
Carrying Value | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	1,086,905	1,106,817
Carrying Value | States and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	1,163,436	1,163,162
Carrying Value | Commercial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	9,624,779	9,386,862
Carrying Value | Commercial real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	12,772,044	12,317,825
Carrying Value | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	6,548,459	6,438,525
Carrying Value | Consumer credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	2,578,381	2,676,758
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, due from banks, money market,    and other interest-earning investments	1,113,935	728,412
Accrued interest receivable	1,046	758
Noninterest-bearing demand deposits	10,995,083	11,930,798
Checking, NOW, savings, and money market    interest-bearing deposits	19,801,014	20,056,252
Time deposits	0	0
Federal funds purchased and interbank borrowings	618,955	581,489
Outstanding at period end	393,018	432,804
Federal Home Loan Bank advances	0	0
Other borrowings	0	0
Accrued interest payable	0	0
Standby letters of credit	0	0
Commitments to extend credit	0	0
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. government-sponsored entities and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	0
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	0
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | States and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	0
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	0	0
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	0	0
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	0	0
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | Consumer credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	0	0
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, due from banks, money market,    and other interest-earning investments	0	0
Accrued interest receivable	43,858	52,081
Noninterest-bearing demand deposits	0	0
Checking, NOW, savings, and money market    interest-bearing deposits	0	0
Time deposits	4,066,499	2,976,389
Federal funds purchased and interbank borrowings	0	0
Outstanding at period end	0	0
Federal Home Loan Bank advances	4,764,172	3,739,780
Other borrowings	717,801	703,156
Accrued interest payable	28,792	19,547
Standby letters of credit	0	0
Commitments to extend credit	0	0
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | U.S. government-sponsored entities and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	663,623
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	973,486
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | States and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	1,026,265
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | Commercial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	0	0
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | Commercial real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	0	0
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	0	0
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | Consumer credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	0	0
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, due from banks, money market,    and other interest-earning investments	0	0
Accrued interest receivable	144,084	137,682
Noninterest-bearing demand deposits	0	0
Checking, NOW, savings, and money market    interest-bearing deposits	0	0
Time deposits	0	0
Federal funds purchased and interbank borrowings	0	0
Outstanding at period end	0	0
Federal Home Loan Bank advances	0	0
Other borrowings	0	0
Accrued interest payable	0	0
Standby letters of credit	846	755
Commitments to extend credit	3,649	3,666
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | U.S. government-sponsored entities and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	0
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	0
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | States and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	0
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | Commercial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	9,477,212	9,066,583
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | Commercial real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	12,477,217	11,867,851
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | Residential real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	5,760,254	5,372,491
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | Consumer credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, net	$ 2,481,269	$ 2,557,115