Investment Securities (Narrative) (Details) $ in Millions	Jun. 30, 2017 USD ($) Securities yr	Dec. 31, 2016 USD ($) Securities
Investment [Line Items]
Private equity investments prohibited by Volker rule	$ 4
Number of HTM investment securities in an unrealized loss position \| Securities	336	642
Number of AFS investment securities in an unrealized loss position \| Securities	1,529	2,398
Carrying value of pledged securities	$ 2,200	$ 1,400
Private Equity Investments	140
Commitments for Private Equity and Other Noninterest-bearing Investments	27
Commitments for Private Equity or Other Non-Interest Bearing Investments Prohibited by the Volcker Rule	$ 4
Small Business Administration Loan-Backed Securities [Member] \| Minimum [Member]
Investment [Line Items]
Investment term of maturity \| yr	5
Small Business Administration Loan-Backed Securities [Member] \| Maximum [Member]
Investment [Line Items]
Investment term of maturity \| yr	25
US States and Political Subdivisions Debt Securities [Member]
Investment [Line Items]
Held-to-maturity, Amortized cost	$ 775	$ 868

Line items represent reporting concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 12
-Sentence Column A

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Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

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Disclosure regarding factors used to determine that the impairment of securities categorized as held-to-maturity where cost exceeds fair value is not an other than temporary impairment (OTTI). This item contains disclosure of the number of investment positions in the held-to-maturity investments determined to be temporarily impaired.

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Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729

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Held-to-maturity securities, debt maturities, amortized cost.

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Private Equity Investments

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