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Stockholders' Equity - Summary of Assumptions Used to Value Stock Option Grants Using Lattice-Binomial Model (Details)
$ / shares in Units, $ in Thousands
3 Months Ended
Mar. 31, 2018
USD ($)
$ / shares
Mar. 31, 2017
USD ($)
$ / shares
Stockholders' Equity and Stock-based Compensation Disclosure [Abstract]    
Share-based payment award, expiration period (in years) 10 years  
Dividend yield 0.00% 0.00%
Expected volatility 40.00% 37.00%
Risk-free interest rate 2.61% 2.45%
Suboptimal exercise factor 2.80 2.48
Weighted-average fair value (in dollars per share) | $ / shares $ 123.63 $ 62.36
Stock-based compensation expense $ 68,395 $ 44,888
Total income tax impact on provision (in thousands) $ 14,691 $ 14,701