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STOCKHOLDERS' EQUITY - Summary of Restricted Stock, Restricted Stock Unit and Performance-based Stock Unit Activity (Detail)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended
Mar. 31, 2018
USD ($)
$ / shares
shares
Restricted Stock, Restricted Stock Units, and Performance-Based Stock Units  
Restricted Stock, Restricted Stock Units, and Performance Stock Units  
Outstanding at beginning of period (in shares) 1,091
Granted (in shares) 201
Forfeited (in shares) 0
Outstanding at end of period (in shares) 952
Unvested, at end of period (in shares) 1,402
Weighted Average Grant Date Fair Value  
Outstanding at beginning of period (in dollars per share) | $ / shares $ 9.81
Granted (in dollars per share) | $ / shares 24.96
Forfeited (in dollars per share) | $ / shares 0.00
Outstanding at end of period (in dollars per share) | $ / shares 14.29
Unvested at end of period (in dollars per share) | $ / shares $ 14.56
Weighted Average Remaining Contractual Term (in years) and Aggregate Intrinsic Value  
Weighted Average Remaining Contractual Term, Outstanding 1 year 7 months 3 days
Weighted Average Remaining Contractual Term, Unvested 1 year 6 months 25 days
Aggregate Intrinsic Value, Outstanding at end of period | $ $ 8,977
Aggregate Intrinsic Value, Unvested at end of period | $ $ 12,914
Performance-Based Stock Units  
Weighted Average Remaining Contractual Term (in years) and Aggregate Intrinsic Value  
Performance-based stock units, percentage of attainment level 100.00%
Class A Common Stock | Restricted Stock, Restricted Stock Units, and Performance-Based Stock Units  
Restricted Stock, Restricted Stock Units, and Performance Stock Units  
Class A Common Stock Vested (in shares) (340)
Weighted Average Grant Date Fair Value  
Class A Common Stock Vested (in dollars per share) | $ / shares $ 6.20
Class A Common Stock | Performance-Based Stock Units  
Weighted Average Remaining Contractual Term (in years) and Aggregate Intrinsic Value  
Number of performance-based stock units (in shares) 450