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Stock-Based Compensation - Summary of Restricted Stock, Restricted Stock Units and Performance-Based Restricted Stock Units (Detail) - $ / shares
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Restricted Stock      
Shares              
Unvested balance, Beginning balance (in shares) 0 21,677 210,083
Granted (in shares) 0 0 0
Vested (in shares) 0 (21,677) (187,706)
Forfeited (in shares) 0 0 (700)
Unvested balance, Ending balance (in shares) 0 0 21,677
Weighted- Average Grant Date Fair Value      
Beginning balance (in dollars per share) $ 0 $ 10.88 $ 18.00
Granted (in dollars per share) 0 0 0
Vested (in dollars per share) 0 10.88 18.80
Forfeited (in dollars per share) 0 0 23.01
Ending Balance (in dollars per share) $ 0 $ 0 $ 10.88
RSUs and PSUs      
Shares              
Unvested balance, Beginning balance (in shares) 2,936,924 2,773,773 1,988,509
Granted (in shares) 1,725,531 1,740,299 2,099,394
Vested (in shares) (1,451,618) (1,291,932) (973,443)
Forfeited (in shares) (268,923) (285,216) (340,687)
Unvested balance, Ending balance (in shares) 2,941,914 2,936,924 2,773,773
Weighted- Average Grant Date Fair Value      
Beginning balance (in dollars per share) $ 32.43 $ 21.21 $ 14.77
Granted (in dollars per share) 57.57 43.34 25.19
Vested (in dollars per share) 33.66 24.42 17.41
Forfeited (in dollars per share) 40.56 26.14 18.96
Ending Balance (in dollars per share) $ 45.86 $ 32.43 $ 21.21