For investments which are quantified by principal amount, the principle balance held at close of period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 946

-SubTopic 320

-Section S99

-Paragraph 6

-Subparagraph (SX 210.12-14.Column B)

-URI http://asc.fasb.org/extlink&oid=34726532&loc=d3e611322-123010

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 946

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-Section S99

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-Subparagraph (SX 210.12-12.Column B)

-URI http://asc.fasb.org/extlink&oid=34726532&loc=d3e611133-123010

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 946

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-Section S99

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-URI http://asc.fasb.org/extlink&oid=34726532&loc=d3e611225-123010

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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-Name Regulation S-X (SX)

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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Name:	us-gaap_InvestmentOwnedBalancePrincipalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Contingencies - Additional Information (Detail) $ in Millions	24 Months Ended
	Dec. 31, 2009 interest_plan	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Loss Contingencies [Line Items]
Carried interest plans \| interest_plan	2
Carried interest rate	15.00%
Plan investment deployed amount approximately			$ 25.5
Maximum
Loss Contingencies [Line Items]
Plan investment deployed amount approximately		$ 79.0