STOCKHOLDERS' EQUITY - Summary of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Stock Options
Beginning balance, outstanding (in shares)	727
Granted (in shares)	0
Exercised (in shares)	(83)
Forfeited (in shares)	0
Ending balance, outstanding (in shares)	644
Exercisable at end of period (in shares)	444
Unvested at end of period (in shares)	240
Weighted Average Exercise Price
Beginning balance, Outstanding (in dollars per share) | $ / shares	$ 5.82
Granted (in dollars per share) | $ / shares	0.00
Exercised (in dollars per share) | $ / shares	4.80
Forfeited (in dollars per share) | $ / shares	0.00
Beginning balance, Outstanding (in dollars per share) | $ / shares	5.95
Exercisable at end of period (in dollars per share) | $ / shares	4.81
Unvested at end of period (in dollars per share) | $ / shares	$ 9.16
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Weighted Average Remaining Contractual Term, Outstanding	6 years
Weighted Average Remaining Contractual Term, Exercisable	5 years 2 months
Weighted Average Remaining Contractual Term, Unvested	7 years 9 months
Aggregate Intrinsic Value, Outstanding at end of period | $	$ 12,651
Aggregate Intrinsic Value, Exercisable at end of period | $	9,228
Aggregate Intrinsic Value, Unvested at end of period | $	$ 3,948
Market-based Performance Stock Options
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Percentage of vesting of share-based compensation awards	100.00%
Issuance of additional shares (in shares)	40