Fair Value Measurements - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 9,198,374	$ 8,687,276	$ 7,618,083	$ 12,028,132
Securities held to maturity, net of allowance for credit losses of $310 at both September 30, 2024 and December 31, 2023	3,569,718	3,619,428
Loans, net	19,791,734	18,578,255
Deposits	41,720,621	41,920,568
Federal funds purchased	22,375	14,200
Repurchase agreements	4,014,037	4,127,188
Junior subordinated deferrable interest debentures	123,170	123,127
Subordinated notes	99,609	99,491
Carrying Amount [Member] \| Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	9,198,374	8,687,276
Securities held to maturity, net of allowance for credit losses of $310 at both September 30, 2024 and December 31, 2023	3,569,718	3,619,428
Accrued interest receivable	194,562	251,385
Deposits	41,720,621	41,920,568
Federal funds purchased	22,375	14,200
Repurchase agreements	4,014,037	4,127,188
Junior subordinated deferrable interest debentures	123,170	123,127
Subordinated notes	99,609	99,491
Accrued interest payable	66,462	61,222
Carrying Amount [Member] \| Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	19,791,734	18,578,255
Estimated Fair Value [Member] \| Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	9,198,374	8,687,276
Securities held to maturity, net of allowance for credit losses of $310 at both September 30, 2024 and December 31, 2023	3,498,271	3,532,044
Accrued interest receivable	194,562	251,385
Deposits	41,712,765	41,903,580
Federal funds purchased	22,375	14,200
Repurchase agreements	4,014,037	4,127,188
Junior subordinated deferrable interest debentures	123,712	123,712
Subordinated notes	99,319	96,071
Accrued interest payable	66,462	61,222
Estimated Fair Value [Member] \| Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	$ 19,490,209	$ 18,117,369

Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, 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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Amount, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

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The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

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

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Amount of interest payable on debt, including, but not limited to, trade payables.

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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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