Investment Securities (Investment Income) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Taxable interest	$ 654	$ 858	$ 690
Taxable dividends	21	14	14
Interest and dividends exempt from U.S. federal income tax	17	15	25
Interest and dividends on investment securities and other earning assets	736	955	788
Excludes other earning assets
Interest and dividends on investment securities and other earning assets	$ 692	$ 887	$ 729

Amount of operating dividend income on securities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.2)
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

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Amount of operating dividend and interest income, including amortization and accretion of premiums and discounts, on securities.

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Interest income, including any amortization and accretion (as applicable) of discounts and premiums, derived from debt securities issued by municipal governments, local taxing districts and US state government agencies.

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Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities subject to state, federal and other income tax.

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