Investment Securities - Investment Securities in an Unrealized Loss Position (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
AFS: Fair Value, Less than 12 Months	$ 46,955	$ 8,824
AFS: Fair Value, 12 Months or Longer	1,775	2,358
AFS: Fair Value, Total	48,730	11,182
AFS: Gross Unrealized Losses, Less than 12 Months	607	31
AFS: Gross Unrealized Losses, 12 Months or Longer	32	30
AFS: Gross Unrealized Losses, Total	639	61
U.S. Treasury securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
AFS: Fair Value, Less than 12 Months	31,459	151
AFS: Fair Value, Total	31,459	151
AFS: Gross Unrealized Losses, Less than 12 Months	296	0
AFS: Gross Unrealized Losses, Total	296	0
U.S. agency securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
AFS: Fair Value, Less than 12 Months	12,283	5,808
AFS: Fair Value, 12 Months or Longer	1,167	1,168
AFS: Fair Value, Total	13,450	6,976
AFS: Gross Unrealized Losses, Less than 12 Months	219	22
AFS: Gross Unrealized Losses, 12 Months or Longer	22	3
AFS: Gross Unrealized Losses, Total	241	25
Agency CMBS
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
AFS: Fair Value, Less than 12 Months	2,872	2,779
AFS: Fair Value, 12 Months or Longer	10	46
AFS: Fair Value, Total	2,882	2,825
AFS: Gross Unrealized Losses, Less than 12 Months	89	9
AFS: Gross Unrealized Losses, 12 Months or Longer	0	0
AFS: Gross Unrealized Losses, Total	89	9
State and municipal securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
AFS: Fair Value, Less than 12 Months	21	86
AFS: Fair Value, 12 Months or Longer	7	36
AFS: Fair Value, Total	28	122
AFS: Gross Unrealized Losses, Less than 12 Months	2	0
AFS: Gross Unrealized Losses, 12 Months or Longer	0	1
AFS: Gross Unrealized Losses, Total	2	1
FFELP student loan ABS
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
AFS: Fair Value, Less than 12 Months	320	0
AFS: Fair Value, 12 Months or Longer	591	1,077
AFS: Fair Value, Total	911	1,077
AFS: Gross Unrealized Losses, Less than 12 Months	1	0
AFS: Gross Unrealized Losses, 12 Months or Longer	10	26
AFS: Gross Unrealized Losses, Total	$ 11	$ 26

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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.

+ References

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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.

+ References

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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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