Fair Value Measurements - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 7,144,784	$ 8,687,276	$ 7,107,336	$ 12,028,132
Securities held to maturity, net of allowance for credit losses of $310 at both June 30, 2024 and December 31, 2023	3,586,116	3,619,428
Loans, net	19,739,449	18,578,255
Deposits	40,318,140	41,920,568
Federal funds purchased	35,925	14,200
Repurchase agreements	3,762,942	4,127,188
Junior subordinated deferrable interest debentures	123,155	123,127
Subordinated notes	99,569	99,491
Carrying Amount [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	7,144,784	8,687,276
Securities held to maturity, net of allowance for credit losses of $310 at both June 30, 2024 and December 31, 2023	3,586,116	3,619,428
Accrued interest receivable	243,951	251,385
Deposits	40,318,140	41,920,568
Federal funds purchased	35,925	14,200
Repurchase agreements	3,762,942	4,127,188
Junior subordinated deferrable interest debentures	123,155	123,127
Subordinated notes	99,569	99,491
Accrued interest payable	66,812	61,222
Carrying Amount [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	19,739,449	18,578,255
Estimated Fair Value [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	7,144,784	8,687,276
Securities held to maturity, net of allowance for credit losses of $310 at both June 30, 2024 and December 31, 2023	3,416,937	3,532,044
Accrued interest receivable	243,951	251,385
Deposits	40,303,423	41,903,580
Federal funds purchased	35,925	14,200
Repurchase agreements	3,762,942	4,127,188
Junior subordinated deferrable interest debentures	123,712	123,712
Subordinated notes	96,645	96,071
Accrued interest payable	66,812	61,222
Estimated Fair Value [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	$ 19,241,857	$ 18,117,369