Aggregate number of common shares reserved for future issuance.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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Unrecognized cost of unvested options awarded to employees as compensation.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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General descriptive information regarding an arrangement under which employees and directors receive: (a) awards of equity shares, equity share options, or other equity instruments; or (b) the entity incurs liabilities to them: (1) in amounts based, at least in part, on the price of the entity's shares or other equity instruments; or (2) that require or may require settlement by issuance of the entity's shares. Such an arrangement is usually provided to employees and directors to compensate them, provide performance incentives to them, and to attract or retain their services. May also include pertinent information particular to a plan that is not elsewhere specified in the taxonomy.

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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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Number of additional shares authorized for issuance under an established share-based compensation plan.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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Number of share instruments newly issued under a share-based compensation plan.

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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Share-Based Compensation - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Sep. 30, 2014	Sep. 30, 2018	Nov. 30, 2017	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, description		Options and restricted stock units granted to our non-employee directors vest in full upon completion of one year of service on the Board following the date of the grant.
Total unrecognized share-based compensation cost related to stock options		$ 0.0
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period of share-based compensation vested, years		4 years
Stock options [Member] \| Share-based compensation granted after December 5, 2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expire from date of grant, years		8 years
Stock options [Member] \| Share-based compensation granted prior to December 5, 2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expire from date of grant, years		10 years
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period of share-based compensation vested, years	4 years
Total unrecognized share-based compensation cost related to RSUs		$ 69.8
Total unrecognized share-based compensation cost, weighted-average period, years		2 years 8 months 12 days
Restricted Stock Units (RSUs) [Member] \| Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period of share-based compensation vested, years		1 year
The 2017 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares approved			1,400,000
Common stock shares available for issuance		400,000
The 2017 Plan [Member] \| Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant		600,000
The 2010 Plan [Member] \| Options and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant		5,700,000
2012 Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares approved				2,000,000
Shares issued under the Plan		700,000