STOCK INCENTIVE PLANS - Components of Restricted Stock Units (Detail) $ in Thousands	6 Months Ended
Jun. 30, 2018 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock units (in shares) \| shares	2,512,711
Unrecognized compensation expense	$ 19,051
Intrinsic value	$ 33,721
Weighted average remaining life (in years)	2 years 2 months 7 days
Service-Based Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock units (in shares) \| shares	1,449,400
Unrecognized compensation expense	$ 12,405
Intrinsic value	$ 19,451
Weighted average remaining life (in years)	2 years 3 months 13 days
Performance-Based Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock units (in shares) \| shares	1,063,311
Unrecognized compensation expense	$ 6,646
Intrinsic value	$ 14,270
Weighted average remaining life (in years)	2 years 18 days

Unrecognized cost of unvested share-based compensation awards.

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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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Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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 by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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