Share-based Compensation - Summary of Stock Option Activities (Details) - $ / shares	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Number of Stock Options
Number of Options, Options outstanding, beginning of period	33,503
Number of Options, Forfeited and cancelled	(222)
Number of Options, Options outstanding, end of period	33,281	33,503
Number of Options, Options exercisable, end of period	28,487
Number of Options, Options vested and expected to vest	33,276
Stock Options, Weighted Average Exercise Price
Weighted Average Exercise Price, Options outstanding, beginning of period	$ 96.22
Weighted Average Exercise Price, Forfeited and cancelled	1,579.97
Weighted Average Exercise Price, Options outstanding, end of period	86.32	$ 96.22
Weighted Average Exercise Price, Options exercisable, end of period	93.61
Weighted Average Exercise Price, Options vested and expected to vest, end of period	$ 86.33
Stock Options, Weighted Average Remaining Contractual Term
Weighted Average Remaining Contractual Term (in years), Options outstanding	6 years 11 months 23 days	7 years 3 months 14 days
Weighted Average Remaining Contractual Term (in years), Options exercisable	6 years 10 months 6 days
Weighted Average Remaining Contractual Term (in years), Options vested and expected to vest	6 years 11 months 23 days

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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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For presentations that combine terminations, 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 or that expired.

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Weighted average price of options that were either forfeited or expired.

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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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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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

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

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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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