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 options awarded to employees as compensation.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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

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

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Stock-Based Compensation - Additional Information (Detail) - USD ($)		6 Months Ended
	Jan. 04, 2016	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted		719,000
Number of options exercised		24,000
Aggregate intrinsic value of stock options exercised		$ 235,000
Options to purchase common stock, outstanding		2,300,000	1,723,000	1,657,000
Weighted average remaining contractual term		8 years 1 month 6 days	8 years 3 months 18 days
Weighted average exercise price		$ 15.07	$ 14.23	$ 14.28
Weighted average grant date fair value of options granted		$ 11.85	$ 15.67
Unrecognized stock-based compensation expense		$ 10,836,000	$ 13,912,000
Unrecognized compensation costs, weighted-average recognition periods		2 years 8 months 12 days	2 years 10 months 24 days
Performance-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of restricted common stock units granted under performance-based vesting		194,000
Number of RSUs, Cancelled		5,000
Performance based RSUs vested		0
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of restricted common stock units granted under performance-based vesting	189,300
Grant date fair value of restricted common stock units under performance-based vesting	$ 3,445,000