Investment Securities - Schedule of Unrealized Losses (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Investment securities available for sale:
Investment securities available for sale, less than 12 months, fair value	$ 7,130	$ 6,724
Investment securities available for sale, less than 12 months, unrealized losses	(368)	(54)
Investment securities available for sale, 12 months or more, fair value	1,229	191
Investment securities available for sale, 12 months or more, unrealized losses	(74)	(3)
Investment securities available for sale, fair value	8,359	6,915
Investment securities available for sale, unrealized losses	(442)	(57)
U.S. Treasury
Investment securities available for sale:
Investment securities available for sale, less than 12 months, fair value	1,931	1,811
Investment securities available for sale, less than 12 months, unrealized losses	(83)	(2)
Investment securities available for sale, 12 months or more, fair value	0	0
Investment securities available for sale, 12 months or more, unrealized losses	0	0
Investment securities available for sale, fair value	1,931	1,811
Investment securities available for sale, unrealized losses	(83)	(2)
Government agency
Investment securities available for sale:
Investment securities available for sale, less than 12 months, fair value	21	17
Investment securities available for sale, less than 12 months, unrealized losses	0	0
Investment securities available for sale, 12 months or more, fair value	74	79
Investment securities available for sale, 12 months or more, unrealized losses	(1)	(1)
Investment securities available for sale, fair value	95	96
Investment securities available for sale, unrealized losses	(1)	(1)
Residential mortgage-backed securities
Investment securities available for sale:
Investment securities available for sale, less than 12 months, fair value	4,247	3,992
Investment securities available for sale, less than 12 months, unrealized losses	(239)	(36)
Investment securities available for sale, 12 months or more, fair value	670	1
Investment securities available for sale, 12 months or more, unrealized losses	(49)	0
Investment securities available for sale, fair value	4,917	3,993
Investment securities available for sale, unrealized losses	(288)	(36)
Commercial mortgage-backed securities
Investment securities available for sale:
Investment securities available for sale, less than 12 months, fair value	744	852
Investment securities available for sale, less than 12 months, unrealized losses	(42)	(15)
Investment securities available for sale, 12 months or more, fair value	485	111
Investment securities available for sale, 12 months or more, unrealized losses	(24)	(2)
Investment securities available for sale, fair value	1,229	963
Investment securities available for sale, unrealized losses	(66)	(17)
Corporate bonds
Investment securities available for sale:
Investment securities available for sale, less than 12 months, fair value	187	52
Investment securities available for sale, less than 12 months, unrealized losses	(4)	(1)
Investment securities available for sale, 12 months or more, fair value	0	0
Investment securities available for sale, 12 months or more, unrealized losses	0	0
Investment securities available for sale, fair value	187	52
Investment securities available for sale, unrealized losses	$ (4)	$ (1)

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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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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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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 less 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 less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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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 unrealized loss position without allowance for credit loss.

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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 unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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