Securities - Summary Of Government-Sponsored Residential Mortgage-Backed Securities With Gross Unrealized Losses (Detail) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings	470	6
Less than 12 months, gross unrealized losses	$ 85,764	$ 3,872
Less than 12 months, fair value	5,993,147	416,824
12 months or longer, gross unrealized losses	26,683	0
12 months or longer, fair value	810,035	0
Gross Unrealized Losses	112,447	3,872
Fair Value	$ 6,803,182	$ 416,824
Government-sponsored residential mortgage-backed securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings	264
Less than 12 months, gross unrealized losses	$ 70,502
Less than 12 months, fair value	4,615,457
12 months or longer, gross unrealized losses	0
12 months or longer, fair value	0
Gross Unrealized Losses	70,502
Fair Value	$ 4,615,457
Government-sponsored commercial mortgage-backed securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings	165
Less than 12 months, gross unrealized losses	$ 12,218
Less than 12 months, fair value	1,102,444
12 months or longer, gross unrealized losses	422
12 months or longer, fair value	15,682
Gross Unrealized Losses	12,640
Fair Value	$ 1,118,126
U.S. Agency bonds
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings	27	6
Less than 12 months, gross unrealized losses	$ 2,169	$ 3,872
Less than 12 months, fair value	191,222	416,824
12 months or longer, gross unrealized losses	26,261	0
12 months or longer, fair value	794,353	0
Gross Unrealized Losses	28,430	3,872
Fair Value	$ 985,575	$ 416,824
U.S. Treasury securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings	3
Less than 12 months, gross unrealized losses	$ 834
Less than 12 months, fair value	78,588
12 months or longer, gross unrealized losses	0
12 months or longer, fair value	0
Gross Unrealized Losses	834
Fair Value	$ 78,588
State and municipal bonds and obligations
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings	11
Less than 12 months, gross unrealized losses	$ 41
Less than 12 months, fair value	5,436
12 months or longer, gross unrealized losses	0
12 months or longer, fair value	0
Gross Unrealized Losses	41
Fair Value	$ 5,436

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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