STOCK BASED COMPENSATION - Summary of PSU Activity (Detail) - Performance-Based Restricted Stock Units	9 Months Ended
Sep. 30, 2018 $ / shares shares
Number of Units
Non-vested at January 1, 2018 \| shares	11,149
Granted \| shares	131,182
Forfeited \| shares	(24,579)
Non-vested as of September 30, 2018 \| shares	117,752
Weighted Average Grant Date Fair Value Per Share
Non-vested at January 1, 2018 \| $ / shares	$ 82.85
Granted \| $ / shares	63.92
Forfeited \| $ / shares	72.23
Non-vested as of September 30, 2018 \| $ / shares	$ 63.98

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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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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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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Number of shares related to Restricted Stock Award forfeited during the period.

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