Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Held to maturity securities	$ 2,825,064	$ 2,852,495
Loans held for sale	14,923	10,843
Derivative assets	89,182	110,734
Derivative liabilities	85,772	32,601
Total Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, interest-bearing bank deposits, and federal funds sold	2,882,521	888,519
Available for sale securities	5,565,620	5,556,041
Held to maturity securities	2,623,760	2,615,398
Loans, net	22,984,009	22,137,375
Loans held for sale	23,436	26,385
Derivative assets	91,945	109,497
Deposits	29,587,071	29,041,635
Federal funds purchased	350	1,850
Securities sold under agreements to repurchase	419,147	444,421
FHLB short-term borrowings	3,100,275	1,425,000
Long-term debt	206,659	200,060
Derivative liabilities	216,201	204,121
Total Fair Value [Member] \| Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, interest-bearing bank deposits, and federal funds sold	2,882,521	888,519
Federal funds purchased	350	1,850
Securities sold under agreements to repurchase	419,147	444,421
FHLB short-term borrowings		1,425,000
Total Fair Value [Member] \| Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Available for sale securities	5,565,620	5,556,041
Held to maturity securities	2,623,760	2,615,398
Loans, net	13,212	4,692
Loans held for sale	23,436	26,385
Derivative assets	91,945	109,497
FHLB short-term borrowings	3,100,275
Long-term debt	206,659	200,060
Derivative liabilities	214,798	202,238
Total Fair Value [Member] \| Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans, net	22,970,797	22,132,683
Deposits	29,587,071	29,041,635
Derivative liabilities	1,403	1,883
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, interest-bearing bank deposits, and federal funds sold	2,882,521	888,519
Available for sale securities	5,565,620	5,556,041
Held to maturity securities	2,825,064	2,852,495
Loans, net	23,095,138	22,806,257
Loans held for sale	23,436	26,385
Derivative assets	91,945	109,497
Deposits	29,613,070	29,070,349
Federal funds purchased	350	1,850
Securities sold under agreements to repurchase	419,147	444,421
FHLB short-term borrowings	3,100,000	1,425,000
Long-term debt	242,115	242,077
Derivative liabilities	$ 216,201	$ 204,121

Equity and debt available for sale securities.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value portion of short term borrowing where a bank borrows, at the federal funds rate, from another bank.

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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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Amount, before allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

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Amortized cost, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

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Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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