Income Taxes - Reconciliation of 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 Disclosure [Abstract]
Beginning Balance	$ 287us-gaap_UnrecognizedTaxBenefits	$ 73us-gaap_UnrecognizedTaxBenefits	$ 62us-gaap_UnrecognizedTaxBenefits
Increase/(Decrease) of unrecognized tax benefits taken in prior years		31
Increase/(Decrease) of unrecognized tax benefits related to current year		183	11
Decreases based on tax positions taken during a prior period	(102)
Increases based on tax positions taken during a current period	147
Ending Balance	$ 332us-gaap_UnrecognizedTaxBenefits	$ 287us-gaap_UnrecognizedTaxBenefits	$ 73us-gaap_UnrecognizedTaxBenefits

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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

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- Definition

Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

+ 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)(1)

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

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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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- Definition

Increase decrease of unrecognized tax benefits related to current year.

+ References

No definition available.

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- Definition

Increase decrease of unrecognized tax benefits taken in prior years.

+ References

No definition available.

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