Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) (Recurring [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Assets
Money market funds	$ 36,779us-gaap_AssetsFairValueDisclosure	$ 5,204us-gaap_AssetsFairValueDisclosure
Liabilities
Contingent consideration	1,074
Warrants to purchase convertible preferred stock		525
Total liabilities	1,074us-gaap_LiabilitiesFairValueDisclosure	525us-gaap_LiabilitiesFairValueDisclosure
Fair Value Measured Using - (Level 1) [Member]
Assets
Money market funds	36,779	5,204
Liabilities
Contingent consideration	0
Warrants to purchase convertible preferred stock		0
Total liabilities	0	0
Fair Value Measured Using - (Level 2) [Member]
Assets
Money market funds	0	0
Liabilities
Contingent consideration	0
Warrants to purchase convertible preferred stock		0
Total liabilities	0	0
Fair Value Measured Using - (Level 3) [Member]
Assets
Money market funds	0	0
Liabilities
Contingent consideration	1,074
Warrants to purchase convertible preferred stock		525
Total liabilities	$ 1,074	$ 525

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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- Definition

Fair value of contingent consideration in a business combination that is classified in shareholders' equity.

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- Definition

Fair value of financial and nonfinancial obligations.

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- Definition

Fair value portion of shares that an entity is required to redeem for cash or other assets at a fixed or determinable date or upon the occurrence of an event.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Section 25

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6939902&loc=d3e21216-110875

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