Variable Interest Entities - Additional Information (Detail)	9 Months Ended
Sep. 30, 2014 Investment Entity Assets
Variable Interest Entity or Potential VIE, Information Unavailability, Disclosures [Abstract]
Number of identified consolidated variable interest entities	2
Identified investments	6
Investments with no equity at risk	2
Number of additional entities	4
Number of assets identified as variable interests in variable interest entities	2
Investments lacking the right to receive returns	1

Number of Variable Interest Entities (VIE) or potential VIEs for which the necessary information is unable to be obtained to: (1) determine whether the legal entity is a VIE, (2) determine whether it (the reporting entity) is the VIE's primary beneficiary, or (3) perform the accounting required to consolidate the VIE for which it is determined that it (the reporting entity) is the primary beneficiary.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph a

-URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5747-111685

Name:	us-gaap_VariableInterestEntityNumberOfEntitiesWithUnavailabilityOfInformation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration