Condensed Financial Statements of Parent Company (Schedule of Condensed Balance Sheets) (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Statements, Captions [Line Items]
Cash	$ 555,778	$ 529,454
Resell agreements	7,903	0
Cash and cash equivalents	16,583,000	10,288,853	$ 3,788,181	$ 3,955,779
Total assets	50,878,490	42,391,317
Junior subordinated deferrable interest debentures, net of unamortized issuance costs	123,011	136,357
Subordinated notes, net of unamortized issuance costs	99,178	99,021
Accrued interest payable and other liabilities	754,326	730,165
Total liabilities	46,438,935	38,098,301
Shareholders’ Equity	4,439,555	4,293,016	$ 3,911,668	$ 3,368,917
Total liabilities and shareholders’ equity	50,878,490	42,391,317
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Cash	471,875	381,240
Resell agreements	0	0
Cash and cash equivalents	471,875	381,240
Investment in subsidiaries	4,222,288	4,155,619
Accrued interest receivable and other assets	2,228	2,164
Total assets	4,696,391	4,539,023
Junior subordinated deferrable interest debentures, net of unamortized issuance costs	123,011	136,357
Subordinated notes, net of unamortized issuance costs	99,178	99,021
Accrued interest payable and other liabilities	34,647	10,629
Total liabilities	256,836	246,007
Shareholders’ Equity	4,439,555	4,293,016
Total liabilities and shareholders’ equity	$ 4,696,391	$ 4,539,023