Convertible and Redeemable Convertible Preferred Stock - Summary of Assumptions used to Determine Fair Value of Temporary Equity (Detail)	6 Months Ended	12 Months Ended
Jun. 30, 2015	Dec. 31, 2014
Temporary Equity [Line Items]
Expected term (in years)	10 months 24 days
Expected volatility	66.00%
Risk-free interest rate	0.20%
Expected dividend rate	0.00%	0.00%
Minimum [Member]
Temporary Equity [Line Items]
Expected term (in years)		1 year 2 months 12 days
Expected volatility		69.00%
Risk-free interest rate		0.30%
Maximum [Member]
Temporary Equity [Line Items]
Expected term (in years)		2 years 6 months
Expected volatility		86.00%
Risk-free interest rate		0.60%

Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (e)

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

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- Definition

Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

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Risk-free interest rate assumption used in valuing an instrument.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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