Cash and Cash Equivalents (Footnote Information) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Cash and Cash Equivalents [Abstract]
Deposits at the Federal Reserve Bank earning interest at the Federal Funds target rate	$ 861	$ 715
Interest-earning deposits in other financial institutions	440us-gaap_InterestBearingDepositsInBanks	300us-gaap_InterestBearingDepositsInBanks
Fair value of securities purchased under agreements to resell	98	176
Fair value of securities received as collateral that have been resold or repledged	$ 0	$ 0

Interest bearing Deposits in Federal Reserve Banks

No definition available.

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- Details

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- Definition

Fair value of collateral permitted, by contact or custom, to be sold or re-pledged.

+ 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 (c)(1)

-URI http://asc.fasb.org/extlink&oid=34720971&loc=SL6224234-111729

+ Details

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- Definition

Fair value of the collateral, or portion thereof, that has been re-pledged, delivered, or otherwise used.

+ 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 (c)(2)

-URI http://asc.fasb.org/extlink&oid=34720971&loc=SL6224234-111729

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- Definition

For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6476743&loc=d3e59706-112781

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 2

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.2)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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