Securities - Gross Unrealized Losses and Related Fair Values (Detail) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale gross unrealized losses one year or less	$ (30)	$ (1)
Securities available-for-sale aggregate fair value of investment one year or less	9,533	1,720
Securities available-for-sale gross unrealized losses greater than one year	(1,760)	(1,676)
Securities available-for-sale aggregate fair value of investment greater than one year	12,858	13,409
U.S. Treasury
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale gross unrealized losses one year or less	(20)	0
Securities available-for-sale aggregate fair value of investment one year or less	5,722	0
Securities available-for-sale gross unrealized losses greater than one year	(153)	(107)
Securities available-for-sale aggregate fair value of investment greater than one year	3,135	3,419
U.S. Government sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale gross unrealized losses one year or less	0	0
Securities available-for-sale aggregate fair value of investment one year or less	0	0
Securities available-for-sale gross unrealized losses greater than one year	(813)	(808)
Securities available-for-sale aggregate fair value of investment greater than one year	3,511	3,592
U.S. Government agency issued or guaranteed
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale gross unrealized losses one year or less	(8)	0
Securities available-for-sale aggregate fair value of investment one year or less	1,583	50
Securities available-for-sale gross unrealized losses greater than one year	(785)	(752)
Securities available-for-sale aggregate fair value of investment greater than one year	6,128	6,313
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale gross unrealized losses one year or less	0	0
Securities available-for-sale aggregate fair value of investment one year or less	0	129
Securities available-for-sale gross unrealized losses greater than one year	(9)	(9)
Securities available-for-sale aggregate fair value of investment greater than one year	84	85
Foreign debt securities
Debt Securities, Available-for-sale [Line Items]
Securities available-for-sale gross unrealized losses one year or less	(2)	(1)
Securities available-for-sale aggregate fair value of investment one year or less	2,228	1,541
Securities available-for-sale gross unrealized losses greater than one year	0	0
Securities available-for-sale aggregate fair value of investment greater than one year	$ 0	$ 0

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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Amount of accumulated unrealized loss on 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 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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