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Convertible Senior Notes - Additional Information (Detail)
$ / shares in Units, shares in Millions
 1 Months Ended 3 Months Ended 6 Months Ended
May 02, 2017
USD ($)
d
$ / shares
Nov. 30, 2020
USD ($)
Jun. 30, 2021
USD ($)
shares
Jun. 30, 2021
USD ($)
$ / shares
shares
Dec. 31, 2020
USD ($)
Debt Instrument [Line Items]          
Principal amount     $ 381,200,000 $ 381,200,000 $ 381,300,000
2.25% Convertible Senior Notes due 2024          
Debt Instrument [Line Items]          
Principal amount $ 517,500,000   $ 381,200,000 $ 381,200,000  
Interest rate percentage 2.25%        
Maturity date May 15, 2024        
Aggregate principal amount repurchased   $ 136,200,000      
Aggregate repurchase price paid in cash   $ 186,900,000      
Threshold percentage of common stock price trigger 130.00%        
Common stock price trigger (in USD per share) | $ / shares       $ 98.70  
Threshold common stock trading days | d 20        
Threshold consecutive common stock trading days | d 30        
Convertible senior notes redemption rate 100.00%        
Number of consecutive business days 5 days        
Principal amount on conversion rate $ 1,000        
Minimum percentage of common stock price trigger 98.00%        
Conversion observation period 25 days        
Convertible senior notes convertible in to shares 0.0131711        
Convertible senior notes conversion price (in USD per share) | $ / shares $ 75.92        
Shares issued to settle notes at initial conversion rate (in shares) | shares     5.0 5.0  
Convertible senior note premium 42.50%        
Market price of common stock (in USD per share) | $ / shares $ 53.28        
Convertible senior note carrying value of the liability component $ 368,300,000        
Convertible senior note assumed borrowing rate 7.50%        
Convertible senior note carrying value of the equity component $ 149,200,000        
Convertible senior notes term 7 years        
Discount on liability component, remaining amortization period       2 years 10 months 24 days  
Transaction cost related to issuance of convertible senior notes $ 14,700,000        
Debt instrument events of default percentage of principal and accrued and unpaid interest due and payable upon default 100.00%        
Convertible senior notes fair value     $ 506,600,000 $ 506,600,000 $ 514,300,000