Fair Value Measurements - Additional Information (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Fair Value Disclosures [Abstract]
Liabilities carried at fair value	$ 0	$ 0

Fair value of financial and nonfinancial obligations.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

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

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