Reverse Repurchase and Repurchase Agreements - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Securities Financing Transaction [Line Items]
U.S. and non-U.S. government and agency securities, asset-backed securities and corporate debt	$ 45.2
Securities repledged, delivered or used to settle Securities Sold, Not Yet Purchased	32.1
Pledged securities with carrying value to collateralize its repurchase agreements	$ 75.7	$ 64.5

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=55761124&loc=SL6224234-111729

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

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- Definition

Line items represent financial 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.

+ References

No definition available.

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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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