Stockholders' Equity - RSU, RSA, PSU, and PRSA Activity Under Equity-Based Plans (Details)
 3 Months Ended
Mar. 31, 2018
$ / shares
shares
RSUs  
Number of Units  
Nonvested (in shares) | shares 2,249,661
Granted (in shares) | shares 548,054
Vested (in shares) | shares (286,121)
Forfeited (in shares) | shares (88,396)
Nonvested (in shares) | shares 2,423,198
Weighted-Average Grant Date Fair Value  
Nonvested (in dollars per share) | $ / shares $ 24.83
Granted (in dollars per share) | $ / shares 46.97
Vested (in dollars per share) | $ / shares 23.96
Forfeited (in dollars per share) | $ / shares 25.51
Nonvested (in dollars per share) | $ / shares $ 29.91
PSUs  
Number of Units  
Nonvested (in shares) | shares 453,674
Granted (in shares) | shares 23,842
Vested (in shares) | shares (82,066)
Forfeited (in shares) | shares 0
Nonvested (in shares) | shares 395,450
Weighted-Average Grant Date Fair Value  
Nonvested (in dollars per share) | $ / shares $ 30.72
Granted (in dollars per share) | $ / shares 47.61
Vested (in dollars per share) | $ / shares 33.51
Forfeited (in dollars per share) | $ / shares 0.00
Nonvested (in dollars per share) | $ / shares $ 30.89
RSAs  
Number of Units  
Nonvested (in shares) | shares 0
Granted (in shares) | shares 72,991
Nonvested (in shares) | shares 72,991
Weighted-Average Grant Date Fair Value  
Nonvested (in dollars per share) | $ / shares $ 0.00
Granted (in dollars per share) | $ / shares 47.61
Nonvested (in dollars per share) | $ / shares $ 47.61
PRSAs  
Number of Units  
Nonvested (in shares) | shares 0
Granted (in shares) | shares 169,088
Nonvested (in shares) | shares 169,088
Weighted-Average Grant Date Fair Value  
Nonvested (in dollars per share) | $ / shares $ 0.00
Granted (in dollars per share) | $ / shares 47.61
Nonvested (in dollars per share) | $ / shares $ 47.61