Federal Funds Sold and Securities Borrowed or Purchased Under Agreements to Resell - Additional Information (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Securities Purchased under Agreements to Resell [Abstract]
Collateral Requirements Minimum Percentage Collateral To Fair Value Of Securities Purchased Under Repurchase Agreements	95.00%
Collateral Requirements Maximum Percentage Collateral To Fair Value Of Securities Purchased Under Repurchase Agreements	110.00%
Fair Value of Securities Received as Collateral that Can be Resold or Repledged	$ 1,200,000,000	$ 1,100,000,000
Fair Value of Securities Received as Collateral that Have Been Resold or Repledged	$ 194,000,000	$ 222,000,000

Collateral Requirements Maximum Percentage Collateral To Fair Value Of Securities Purchased or Borrowed Under Repurchase Agreements

No definition available.

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- Definition

Collateral Requirements, Minimum Percentage, Collateral To Fair Value Of Securities Purchased or Borrowed Under Repurchase Agreements

+ References

No definition available.

+ 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

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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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