Variable Interest Entities - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2013
Fair Value Disclosures [Abstract]
Expected settlement period of other liabilities	Within the next sixty days
Transfers from Level II into Level I	$ 164

Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258

Name:	us-gaap_FairValueAssetsLevel2ToLevel1TransfersAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant