Stock-Based Compensation - Summary of PSUs, RSUs and Restricted Stock Outstanding (Detail) shares in Thousands	6 Months Ended
Jun. 30, 2018 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Unvested PSUs, RSUs and restricted stock outstanding, beginning balance \| shares	1,292
Number of Shares, PSUs, RSUs and restricted stock granted \| shares	8
Number of Shares, PSUs, RSUs and restricted stock vested \| shares	(7)
Number of Shares, PSUs, RSUs and restricted stock forfeited \| shares	(105)
Number of Shares, Unvested PSUs, RSUs and restricted stock outstanding, ending balance \| shares	1,188
Weighted Avg. Grant Date Fair Value, Unvested PSUs, RSUs and restricted stock outstanding, Beginning Balance \| $ / shares	$ 21.33
Weighted Avg. Grant Date Fair Value, PSUs, RSUs and restricted stock granted \| $ / shares	20.68
Weighted Avg. Grant Date Fair Value, PSUs, RSUs and restricted stock vested \| $ / shares	19.99
Weighted Avg. Grant Date Fair Value, PSUs, RSUs and restricted stock forfeited \| $ / shares	21.59
Weighted Avg. Grant Date Fair Value, Unvested PSUs, RSUs and restricted stock outstanding, Ending Balance \| $ / shares	$ 21.31

No definition available.

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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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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- Definition

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 weighted average fair value at grant date for nonvested equity-based awards issued 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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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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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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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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