Changes in Amount of Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Beginning balance of unrecognized tax benefits	$ 1,092us-gaap_UnrecognizedTaxBenefits	$ 569us-gaap_UnrecognizedTaxBenefits	$ 406us-gaap_UnrecognizedTaxBenefits
Increase (decrease) for prior year tax positions	(73)	137	50
Increase for current year tax positions	834	386	113
Total	$ 1,853us-gaap_UnrecognizedTaxBenefits	$ 1,092us-gaap_UnrecognizedTaxBenefits	$ 569us-gaap_UnrecognizedTaxBenefits

Unrecognized Tax Benefits, Increases (Decreases) Resulting from Prior Period Tax Positions

No definition available.

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- Definition

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

+ References

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

+ Details

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- Definition

Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15A

-Subparagraph (a)(2)

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

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