Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
Components Of Income Tax Expense Benefit [Line Items]
Change in liability for unrecognized tax benefits	$ 0	$ 0
Unrecognized tax benefits	$ 508,000	$ 508,000	$ 508,000
Period in which unrecognized tax benefits may be changed		12 months

Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

-URI http://asc.fasb.org/extlink&oid=6527854

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15A

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319

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