STOCKHOLDERS' EQUITY - Summary of Restricted Stock, Restricted Stock Unit and Performance Stock Unit Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Restricted Stock, Restricted Stock Units and Performance Stock Units
Restricted Stock, Restricted Stock Units, and Performance Stock Units
Outstanding, beginning balance (in shares)	1,099
Granted (in shares)	439
Forfeited (in shares)	(27)
Outstanding, ending balance (in shares)	1,091
Unvested (in shares)	1,453
Weighted Average Grant Price
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 7.03
Granted (in dollars per share) | $ / shares	12.32
Forfeited (in dollars per share) | $ / shares	6.31
Outstanding, ending balance (in dollars per share) | $ / shares	9.81
Weighted average grant price, unvested, ending balance (in dollars per share) | $ / shares	$ 10.48
Weighted average remaining contractual term, outstanding	1 year 3 months 6 days
Weighted average remaining contractual term, unvested	1 year 3 months 12 days
Aggregate intrinsic value, outstanding | $	$ 14,409
Aggregate intrinsic value, unvested | $	$ 18,216
Performance Stock Units
Weighted Average Grant Price
Attainment level percentage	100.00%
Class A Common Stock | Restricted Stock, Restricted Stock Units and Performance Stock Units
Restricted Stock, Restricted Stock Units, and Performance Stock Units
Vested (in shares)	(420)
Weighted Average Grant Price
Vested (in dollars per share) | $ / shares	$ 5.21
Class A Common Stock | Performance Stock Units
Weighted Average Grant Price
Additional issuance if performance targets met (in shares)	362