Income Taxes - Additional Information (Detail)	6 Months Ended
Jun. 30, 2012
Income Tax Examination [Line Items]
Years subject to tax examination	from 2002 through 2011

A brief description of status of the tax examination, significant findings to date, and the entity's position with respect to the findings.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (d)(2)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319

Name:	us-gaap_IncomeTaxExaminationDescription
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration