v2.4.0.8

Reverse Repurchase and Repurchase Agreements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2013 | Dec. 31, 2012
Securities Financing Transaction [Line Items] |  |
U.S. and non-U.S. government and agency securities, asset-backed securities and corporate debt | $ 95.8 | $ 247.4
Securities repledged, delivered or used to settle Securities Sold, Not Yet Purchased | 92.8 | 226.4
Pledged securities with carrying value to collateralize its repurchase agreements | $ 68.4 | $ 141.9

X
- Definition 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. + 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=7523297&loc=SL6224234-111729 + Details
Name: | us-gaap_CollateralSecuritiesRepledgedDeliveredOrUsed
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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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=7523297&loc=SL6224234-111729 + Details
Name: | us-gaap_FairValueOfSecuritiesReceivedAsCollateralThatHaveBeenResoldOrRepledged
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
Name: | us-gaap_SecuritiesFinancingTransactionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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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 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=7523297&loc=SL6224234-111729 + Details
Name: | us-gaap_SecuritiesReceivedAsCollateralAmountRepledgedAndSold
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration