Stock-Based Compensation - Summary of Option Activity (Details) - $ / shares	9 Months Ended
Sep. 30, 2019
2005 Plan [Member]
Stock Options
Outstanding at January 1, 2019	582,616
Granted	0
Exercised	(1,500)
Canceled	(30,167)
Outstanding at September 30, 2019	550,949
Shares exercisable at September 30, 2019	550,949
Weighted-Average Exercise Price
Outstanding at January 1, 2019	$ 65.72
Granted	0
Exercised	11.20
Canceled	92.11
Outstanding at September 30, 2019	64.43
Shares exercisable at September 30, 2019	$ 64.43
2015 Plan [Member]
Stock Options
Outstanding at January 1, 2019	2,392,567
Granted	1,479,337
Exercised	(1,514)
Canceled	(451,774)
Outstanding at September 30, 2019	3,418,616
Shares exercisable at September 30, 2019	954,785
Shares available for grant at September 30, 2019	233,059
Weighted-Average Exercise Price
Outstanding at January 1, 2019	$ 62.41
Granted	6.15
Exercised	27.42
Canceled	53.23
Outstanding at September 30, 2019	39.29
Shares exercisable at September 30, 2019	$ 89.06

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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