Stock-Based Compensation (Assumptions Used in Estimation of Fair Value of Stock) (Details) - $ / shares	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of options granted	$ 4.38	$ 2.39	$ 1.07
Risk-free interest rate, minimum	1.19%	1.24%	0.54%
Risk-free interest rate, maximum	2.13%	2.22%	1.36%
Dividend yield	0.00%	0.00%	0.00%
Volatility, minimum	53.58%	52.47%	51.55%
Volatility, maximum	68.39%	67.93%	73.72%
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of options granted			$ 0.78
Risk-free interest rate			0.04%
Dividend yield	0.00%	0.00%	0.00%
Volatility			50.80%
Expected term (in years)			6 months
Expected forfeiture rate	5.00%	5.00%	5.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	3 years 11 months 23 days	4 years 14 days	3 years 10 months 28 days
Expected forfeiture rate	0.00%	0.00%	0.00%
Minimum [Member] \| Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of options granted	$ 1.06	$ 0.78
Risk-free interest rate, minimum	0.05%	0.04%
Volatility, minimum	40.79%	50.80%
Expected term (in years)	6 months	6 months
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	7 years 4 months 2 days	6 years 11 months 16 days	7 years 18 days
Expected forfeiture rate	16.33%	23.15%	23.15%
Maximum [Member] \| Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of options granted	$ 3.38	$ 2.08
Risk-free interest rate, maximum	0.35%	0.24%
Volatility, maximum	64.24%	67.57%
Expected term (in years)	2 years	1 year 6 months

Estimated rate of forfeitures.

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

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)(iii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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

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)(ii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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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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.

+ 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)(iv)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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.

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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

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ 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 (d)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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 S99
-Paragraph 1
-Subparagraph (SAB TOPIC 14.D.2)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: 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 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 14
-Section D
-Subsection 2

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