Stock-Based Compensation - Black-Scholes Option-Pricing Model to Determine Fair Value of Assumptions Used for Employee Grants and Non-Employee Grants Stock Options (Detail) - $ / shares	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Employee Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	1.50%	1.60%
Risk-free interest rate, maximum	1.80%	1.90%
Expected volatility	80.00%
Expected volatility, minimum		81.00%
Expected volatility, maximum		91.00%
Dividend yield	0.00%	0.00%
Weighted-average measurement date fair value	$ 12.08	$ 0.53
Employee Grants \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	4 years	5 years
Employee Grants \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 6 months	5 years 7 months 6 days
Non-Employee Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate		2.20%
Risk-free interest rate, minimum	0.00%
Risk-free interest rate, maximum	2.40%
Expected volatility	80.00%	81.00%
Dividend yield	0.00%	0.00%
Weighted-average measurement date fair value	$ 15.25	$ 0.18
Non-Employee Grants \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	8 years 4 months 24 days	9 years 3 months 18 days
Non-Employee Grants \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	9 years 10 months 24 days	9 years 10 months 24 days

Share based compensation arrangement by share based payment award fair value assumptions price.

No definition available.

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

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- Definition

The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

No definition available.

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- Definition

The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

No definition available.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

+ Details

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- Definition

The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

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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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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

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