Summary of Estimated Future Annual Stock-Based Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
2012	$ 4,000
2013	3,364
2014	2,728
2015	2,298
2016	808
Thereafter	1,513
Total	$ 14,711

Share Based Compensation Arrangement by Share Based Payment Award Expected Future Compensation Thereafter

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- Definition

Share Based Compensation Arrangement by Share Based Payment Award Expected Future Compensation Year Five

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Share Based Compensation Arrangement by Share Based Payment Award Expected Future Compensation Year Four

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- Definition

Share Based Compensation Arrangement by Share Based Payment Award Expected Future Compensation Year One

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- Definition

Share Based Compensation Arrangement by Share Based Payment Award Expected Future Compensation Year three

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Share Based Compensation Arrangement by Share Based Payment Award Expected Future Compensation Year Two

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- Definition

As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph h

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (i)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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