Fair Value Measurements - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 13,632,698	$ 16,583,000	$ 16,253,971	$ 10,288,853
Securities held to maturity, net of allowance for credit losses of $158 at September 30, 2022 and $158 at December 31, 2021	2,174,084	1,749,179
Loans, net	16,716,314	16,087,731
Deposits	46,560,186	42,695,696
Federal funds purchased	26,200	25,925
Repurchase agreements	2,082,739	2,740,799
Junior subordinated deferrable interest debentures	123,055	123,011
Subordinated notes	99,295	99,178
Carrying Amount [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	13,632,698	16,583,000
Securities held to maturity, net of allowance for credit losses of $158 at September 30, 2022 and $158 at December 31, 2021	2,174,084	1,749,179
Cash surrender value of life insurance policies	190,368	190,139
Accrued interest receivable	169,540	179,111
Deposits	46,560,186	42,695,696
Federal funds purchased	26,200	25,925
Repurchase agreements	2,082,739	2,740,799
Junior subordinated deferrable interest debentures	123,055	123,011
Subordinated notes	99,295	99,178
Accrued interest payable	9,545	3,026
Carrying Amount [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	16,716,314	16,087,731
Estimated Fair Value [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	13,632,698	16,583,000
Securities held to maturity, net of allowance for credit losses of $158 at September 30, 2022 and $158 at December 31, 2021	1,917,287	1,809,143
Cash surrender value of life insurance policies	190,368	190,139
Accrued interest receivable	169,540	179,111
Deposits	46,538,352	41,343,426
Federal funds purchased	26,200	25,925
Repurchase agreements	2,082,739	2,740,799
Junior subordinated deferrable interest debentures	123,712	123,712
Subordinated notes	96,926	111,430
Accrued interest payable	9,545	3,026
Estimated Fair Value [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	$ 16,163,170	$ 16,079,454