Investment Securities - Summary of Unrealized Losses on Available for Sale Securities (Detail)	Dec. 31, 2021 USD ($) Investment	Dec. 31, 2020 USD ($) Investment
Investments, Unrealized Loss Position [Line Items]
Fair Value of Investments, Less than 12 months	$ 17,596,000,000	$ 4,285,000,000
Unrealized Losses, Less than 12 months (less than $1 million at December 31, 2020 for U.S. Treasury AFS)	(304,000,000)	(15,000,000)
Fair Value of Investments, 12 months or longer	163,000,000	0
Unrealized Losses, 12 months or longer	(9,000,000)	0
Fair Value of Investments	17,759,000,000	4,285,000,000
Unrealized Losses	$ (313,000,000)	$ (15,000,000)
Number of investments in unrealized loss position \| Investment	475	93
Number of investments with unrealized losses greater than 12 months \| Investment	4	0
Investments in our AFS securities portfolio past due	$ 0	$ 0
U.S. treasury securities
Investments, Unrealized Loss Position [Line Items]
Fair Value of Investments, Less than 12 months	7,777,000,000	60,000,000
Unrealized Losses, Less than 12 months (less than $1 million at December 31, 2020 for U.S. Treasury AFS)	(70,000,000)	0
Fair Value of Investments, 12 months or longer	0	0
Unrealized Losses, 12 months or longer	0	0
Fair Value of Investments	7,777,000,000	60,000,000
Unrealized Losses	(70,000,000)	0
U.S. agency debentures
Investments, Unrealized Loss Position [Line Items]
Fair Value of Investments, Less than 12 months	196,000,000	133,000,000
Unrealized Losses, Less than 12 months (less than $1 million at December 31, 2020 for U.S. Treasury AFS)	(4,000,000)	(1,000,000)
Fair Value of Investments, 12 months or longer	0	0
Unrealized Losses, 12 months or longer	0	0
Fair Value of Investments	196,000,000	133,000,000
Unrealized Losses	(4,000,000)	(1,000,000)
Residential mortgage-backed securities \| Agency-issued mortgage-backed securities
Investments, Unrealized Loss Position [Line Items]
Fair Value of Investments, Less than 12 months	8,280,000,000	904,000,000
Unrealized Losses, Less than 12 months (less than $1 million at December 31, 2020 for U.S. Treasury AFS)	(210,000,000)	(1,000,000)
Fair Value of Investments, 12 months or longer	0	0
Unrealized Losses, 12 months or longer	0	0
Fair Value of Investments	8,280,000,000	904,000,000
Unrealized Losses	(210,000,000)	(1,000,000)
Residential mortgage-backed securities \| Agency-issued collateralized mortgage obligations - fixed rate
Investments, Unrealized Loss Position [Line Items]
Fair Value of Investments, Less than 12 months	740,000,000	2,199,000,000
Unrealized Losses, Less than 12 months (less than $1 million at December 31, 2020 for U.S. Treasury AFS)	(9,000,000)	(10,000,000)
Fair Value of Investments, 12 months or longer	0	0
Unrealized Losses, 12 months or longer	0	0
Fair Value of Investments	740,000,000	2,199,000,000
Unrealized Losses	(9,000,000)	(10,000,000)
Agency-issued commercial mortgage-backed securities
Investments, Unrealized Loss Position [Line Items]
Fair Value of Investments, Less than 12 months	603,000,000	989,000,000
Unrealized Losses, Less than 12 months (less than $1 million at December 31, 2020 for U.S. Treasury AFS)	(11,000,000)	(3,000,000)
Fair Value of Investments, 12 months or longer	163,000,000	0
Unrealized Losses, 12 months or longer	(9,000,000)	0
Fair Value of Investments	766,000,000	989,000,000
Unrealized Losses	$ (20,000,000)	$ (3,000,000)

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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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