Stock-Based Compensation - Summary of Significant Ranges of Outstanding and Exercisable Options (Detail) - Options shares in Thousands	12 Months Ended
Dec. 31, 2018 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercisable, Number Outstanding \| shares	34
Exercisable, Weighted Average Remaining Contractual Life	7 years 9 months 10 days
Exercisable, Weighted Average Exercise Price	$ 40.81
$1.57 - $14.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range limit (in dollars per share)	1.57
Upper range limit (in dollars per share)	$ 14.99
Number Outstanding (in shares) \| shares	144
Weighted Average Remaining Contractual Life	9 years 3 months 3 days
Weighted Average Exercise Price (in dollars per share)	$ 2.64
Number Exercisable (in shares) \| shares \| shares	21
Weighted Average Exercise Price (in dollars per share)	$ 3.70
$15.00 - $25.59
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range limit (in dollars per share)	15.00
Upper range limit (in dollars per share)	$ 25.59
Number Outstanding (in shares) \| shares	8
Weighted Average Remaining Contractual Life	3 years 8 months 26 days
Weighted Average Exercise Price (in dollars per share)	$ 15.00
Number Exercisable (in shares) \| shares \| shares	5
Weighted Average Exercise Price (in dollars per share)	$ 15.00
$25.60 - $143.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range limit (in dollars per share)	25.60
Upper range limit (in dollars per share)	$ 143.99
Number Outstanding (in shares) \| shares	3
Weighted Average Remaining Contractual Life	4 years 4 months 9 days
Weighted Average Exercise Price (in dollars per share)	$ 41.88
Number Exercisable (in shares) \| shares \| shares	2
Weighted Average Exercise Price (in dollars per share)	$ 47.10
$144.00 - $409.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range limit (in dollars per share)	144.00
Upper range limit (in dollars per share)	$ 409.99
Number Outstanding (in shares) \| shares	5
Weighted Average Remaining Contractual Life	6 years 7 months 24 days
Weighted Average Exercise Price (in dollars per share)	$ 144.00
Number Exercisable (in shares) \| shares \| shares	5
Weighted Average Exercise Price (in dollars per share)	$ 144.00
$410.00 - $924.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range limit (in dollars per share)	410.0
Upper range limit (in dollars per share)	$ 924.00
Number Outstanding (in shares) \| shares	1
Weighted Average Remaining Contractual Life	5 years 2 months 8 days
Weighted Average Exercise Price (in dollars per share)	$ 430.64
Number Exercisable (in shares) \| shares \| shares	1
Weighted Average Exercise Price (in dollars per share)	$ 430.64
$1.57 - $924.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower range limit (in dollars per share)	1.57
Upper range limit (in dollars per share)	$ 924.00
Number Outstanding (in shares) \| shares	161
Weighted Average Remaining Contractual Life	8 years 9 months 18 days
Weighted Average Exercise Price (in dollars per share)	$ 10.85
Number Exercisable (in shares) \| shares \| shares	34
Weighted Average Exercise Price (in dollars per share)	$ 40.81

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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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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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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.

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

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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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