Investments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Investment Holdings [Line Items]
Proceeds from sales of available-for-sale securities	$ 0	$ 0
Recognized gains (losses) on available-for-sale securities	0	$ 0
Affordable housing project equity method investments	310		$ 298
Contingent liabilities related to affordable housing project equity method investments	71		59
Payment Services [Member]
Investment Holdings [Line Items]
Equity securities without readily determinable fair value	26		42
Other Assets [Member] \| Community Reinvestment Act [Member]
Investment Holdings [Line Items]
Equity method investments	348		336
Other Liabilities [Member] \| Community Reinvestment Act [Member]
Investment Holdings [Line Items]
Contingent liabilities related to equity method investments	$ 86		$ 74

Amount of investment in qualified affordable housing projects.

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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).

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