Maximum dollar amount of common shares allowed to be purchased.

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Share based compensation arrangement by share based payment Award contractual period.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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- Definition

Aggregate number of common shares reserved for future issuance.

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- Definition

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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- Definition

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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- Definition

The amount of plan compensation cost recognized during the period.

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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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- Definition

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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- Definition

The highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

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- Definition

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

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No definition available.

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- Definition

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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- Definition

Purchase price of common stock expressed as a percentage of its fair value.

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No definition available.

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- Definition

Number of shares issued during the period as a result of an employee stock purchase plan.

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Stock-Based Compensation - Additional Information (Detail) - USD ($)			3 Months Ended		6 Months Ended
	Apr. 05, 2019	Apr. 11, 2012	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	May 09, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based compensation cost			$ 21,252,000	$ 10,746,000	$ 39,483,000	$ 18,343,000
Options granted, contractual period, years					10 years
Unrecognized stock-based compensation cost for options			27,744,000		$ 27,744,000
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average remaining requisite vesting period					3 years 10 months 24 days
Restricted Share Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average remaining requisite vesting period					2 years
Unrecognized stock-based compensation cost			21,280,000		$ 21,280,000
Performance Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average remaining requisite vesting period					2 years
Unrecognized stock-based compensation cost			$ 79,204,000		$ 79,204,000
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair value per share allowed to eligible employees to purchase through payroll deductions					90.00%
Maximum percentage of employee's base salary allowed to be purchased			15.00%		15.00%
Maximum dollar amount of common shares allowed to be purchased					$ 25,000
Common shares reserved for issuance			4,200,000		4,200,000
Issuance of common shares under the employee stock purchase plan (in shares)					134,346	114,951
Compensation expense for ESPP			$ 504,000	$ 191,000	$ 274,000	$ 381,000
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award, vesting period, years					4 years
Minimum \| Restricted Share Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award, vesting period, years					3 months
Minimum \| Performance Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award, vesting period, years					6 months
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award, vesting period, years					5 years
Maximum \| Restricted Share Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award, vesting period, years					4 years
Maximum \| Performance Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award, vesting period, years					3 years
2007 Omnibus Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Amended Omnibus Plan, increase in number of common shares authorized for issuance	8,000,000	5,593,200
Number of common shares authorized for issuance	23,000,000	15,000,000
2017 Omnibus Incentive Compensation Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common shares authorized for issuance							15,000,000