Reverse Repurchase and Repurchase Agreements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Securities Financing Transaction [Line Items]
U.S. and non-U.S. government and agency securities, asset-backed securities and corporate debt	$ 79.3
Securities repledged, delivered or used to settle Securities Sold, Not Yet Purchased	79.3
Pledged securities with carrying value to collateralize its repurchase agreements	$ 110.7	$ 44.8

The carrying value as of the balance sheet date of securities received as collateral from a counterparty that were re-pledged, sold, delivered or otherwise reused by the entity.

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

+ Details

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- Definition

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

+ References

+ Details

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- Details

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- Definition

The fair value of collateral received that has been sold or re-pledged and is owed to the debtor (transferor) upon settlement of the related contractual obligation under which it was received.

+ References

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