Investment Securities - Available-for-Sale Securities (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Purchase of AFS securities	$ 408	$ 360	$ 500
Passive interest in private MBS	254	18
AFS securities sold	$ 0	$ 0	432
Gain on AFS securities			$ 7

Interest Retained In Financial Instruments, Owned, Mortgages

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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with interest rate reset through auction process, sold at par value.

+ References

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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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Amount of cash outflow to acquire investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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