Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: 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.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 718
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Unrecognized cost of unvested options awarded to employees as compensation.

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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.

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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.

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- Definition

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

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

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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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

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-Topic 718
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-Section S99
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- Definition

Represents the term of options granted to persons owning stock representing specified percentage of voting power of all classes of stock, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Stock Incentive Plans - Stock-based Compensation (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 29, 2008	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock-based Compensation
Stock-based compensation
Share-based compensation expense (in dollars)		$ 6,378	$ 5,602	$ 3,548
Unrecognized compensation expense (in dollars)		$ 9,300
Period over which unrecognized compensation expense expected to be recognized		2 years 6 months
Stock-based Compensation \| Cost of revenue
Stock-based compensation
Share-based compensation expense (in dollars)		$ 126	100	51
Stock-based Compensation \| Research and development
Stock-based compensation
Share-based compensation expense (in dollars)		1,322	1,178	790
Stock-based Compensation \| Selling and marketing
Stock-based compensation
Share-based compensation expense (in dollars)		1,594	1,326	707
Stock-based Compensation \| General and administrative
Stock-based compensation
Share-based compensation expense (in dollars)		$ 3,336	$ 2,998	$ 2,000
Stock-based Compensation, employees
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Weighted-average volatility, low end of range (as a percent)		52.49%	52.56%	70.19%
Weighted-average volatility, high end of range (as a percent)		56.36%	68.82%	78.54%
Risk-free interest rate, low end of range (as a percent)		1.16%	1.55%	1.66%
Risk-free interest rate, high end of range (as a percent)		2.09%	2.03%	2.04%
Stock-based Compensation, non-employees
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Weighted-average volatility, low end of range (as a percent)		52.77%	64.72%	73.20%
Weighted-average volatility, high end of range (as a percent)		65.85%	74.48%	74.48%
Risk-free interest rate, low end of range (as a percent)		1.39%	1.78%	2.09%
Risk-free interest rate, high end of range (as a percent)		2.30%	2.29%	2.20%
ESPP
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Weighted-average volatility, low end of range (as a percent)		46.38%	53.57%
Weighted-average volatility, high end of range (as a percent)		75.72%	58.10%
Risk-free interest rate, low end of range (as a percent)		0.40%	0.17%
Risk-free interest rate, high end of range (as a percent)		0.50%	0.33%
Minimum \| Stock-based Compensation, employees
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Weighted-average expected term		5 years 6 months	5 years 6 months	5 years 6 months
Minimum \| Stock-based Compensation, non-employees
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Weighted-average expected term		7 years 9 months 18 days	7 years 11 months 1 day	8 years 9 months
Minimum \| ESPP
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Weighted-average expected term		6 months	5 months 27 days
Maximum \| Stock-based Compensation, employees
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Weighted-average expected term		6 years 3 months 7 days	6 years 29 days	6 years 29 days
Maximum \| Stock-based Compensation, non-employees
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Weighted-average expected term		8 years 6 months 22 days	10 years	10 years
Maximum \| ESPP
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Weighted-average expected term		1 year	11 months 27 days
2008 Plan \| Maximum \| Options
Stock-based compensation
Term of options granted	10 years
2008 Plan \| Maximum \| ISO
Stock-based compensation
Term of options granted to a person owning stock representing more than 10% of voting power of all classes of stock	5 years