Stock Based Compensation - Schedule of Outstanding Stock Options (Details)	3 Months Ended
Mar. 31, 2019 $ / shares shares
Number of Options Outstanding \| shares	2,408,885
Weighted-Average Remaining Contractual Life (years)	6 years 7 months 24 days
Weighted-Average Exercise Price	$ 10.73
Number of Options Exercisable \| shares	2,168,304
Weighted-Average Remaining Contractual Life (years)	6 years 5 months 16 days
Weighted-Average Exercise Price, Options Exercisable	$ 11.69
Stock Options [Member] \| Exercise Price Range One [Member]
Range of Exercise Prices, Lower Range	1.75
Range of Exercise Prices, Upper Range	$ 5.00
Number of Options Outstanding \| shares	1,138,099
Weighted-Average Remaining Contractual Life (years)	8 years 4 months 2 days
Weighted-Average Exercise Price	$ 2.13
Number of Options Exercisable \| shares	897,518
Weighted-Average Remaining Contractual Life (years)	8 years 3 months 26 days
Weighted-Average Exercise Price, Options Exercisable	$ 2.17
Stock Options [Member] \| Exercise Price Range Two [Member]
Range of Exercise Prices, Lower Range	5.01
Range of Exercise Prices, Upper Range	$ 11.00
Number of Options Outstanding \| shares	165,834
Weighted-Average Remaining Contractual Life (years)	3 years 8 months 12 days
Weighted-Average Exercise Price	$ 10.98
Number of Options Exercisable \| shares	165,834
Weighted-Average Remaining Contractual Life (years)	3 years 8 months 12 days
Weighted-Average Exercise Price, Options Exercisable	$ 10.98
Stock Options [Member] \| Exercise Price Range Three [Member]
Range of Exercise Prices, Lower Range	11.01
Range of Exercise Prices, Upper Range	$ 15.00
Number of Options Outstanding \| shares	634,025
Weighted-Average Remaining Contractual Life (years)	6 years 18 days
Weighted-Average Exercise Price	$ 13.91
Number of Options Exercisable \| shares	634,025
Weighted-Average Remaining Contractual Life (years)	6 years 18 days
Weighted-Average Exercise Price, Options Exercisable	$ 13.91
Stock Options [Member] \| Exercise Price Range Four [Member]
Range of Exercise Prices, Lower Range	15.01
Range of Exercise Prices, Upper Range	$ 98.28
Number of Options Outstanding \| shares	470,927
Weighted-Average Remaining Contractual Life (years)	4 years 5 months 9 days
Weighted-Average Exercise Price	$ 27.12
Number of Options Exercisable \| shares	470,927
Weighted-Average Remaining Contractual Life (years)	4 years 5 months 9 days
Weighted-Average Exercise Price, Options Exercisable	$ 27.12

The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

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The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

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Weighted average remaining contractual term of exercisable stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

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Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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