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0.25% Convertible Senior Notes, Convertible Note Hedge and Warrant - Additional Information (Detail)
$ / shares in Units, shares in Thousands
1 Months Ended 3 Months Ended 12 Months Ended
Feb. 19, 2019
USD ($)
May 31, 2017
USD ($)
d
$ / shares
Dec. 31, 2019
d
shares
Dec. 31, 2019
USD ($)
shares
Dec. 31, 2017
USD ($)
$ / shares
shares
Dec. 31, 2018
shares
Debt Instrument [Line Items]            
Net proceeds from the debt offering         $ 389,233,000  
Common stock for issuance upon conversion | shares     3,023 3,023   3,823
Sales of warrants         $ 58,880,000  
Warrants, issuance costs       $ 365,000    
Common Stock [Member]            
Debt Instrument [Line Items]            
Warrants, issuance costs $ 400,000          
0.25% Convertible Senior Notes Due 2022 [Member]            
Debt Instrument [Line Items]            
Debt instrument, interest rate, stated percentage   0.25%        
Debt instrument, maturity date       Jun. 01, 2022    
Debt instrument, payment terms       The interest rates are fixed at 0.25% per annum and are payable semi-annually in arrears on June 1 and December 1 of each year, commencing on December 1, 2017.    
Net proceeds from the debt offering   $ 389,200,000        
Principal amount of each convertible note   $ 1,000        
Debt instrument, conversion ratio   10.5519        
Debt instrument, conversion price per share | $ / shares   $ 94.77        
Debt instrument, convertible, threshold trading days | d     20      
Debt instrument, convertible, threshold consecutive trading days | d     30      
Common stock for issuance upon conversion | shares     4,200 4,200   4,200
Debt Instrument, Redemption Price, Percentage   100.00%        
Debt Instrument, Redemption, Description       repurchase price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date.    
Debt instrument convertible, principal amount       $ 8,000    
Carrying amount of equity component   $ 106,000,000        
Debt instrument, effective interest rate   6.95%        
Debt issuance costs   $ 10,800,000        
Number of common shares to be repurchased under convertible note hedge transactions with certain counterparties | shares         4,200 4,200
Hedging option strike price per common stock | $ / shares         $ 94.77  
Cost of convertible note hedge transactions         $ 78,900,000  
Warrants expected to settle, description       The warrants are expected to settle three business days from each trading day commencing on September 1, 2022 and ending on the 79th trading day thereafter.    
Settlement period of warrants excess price over strike price         3 days  
Warrants expected to settle, commencement date       Sep. 01, 2022    
Sales of warrants         $ 58,900,000  
Warrants, issuance costs         200,000  
Convertible notes hedge and warrant transactions cost net         20,000,000  
Reserved common stock for underlying warrants | shares           4,200
Deferred tax liability adjustment to additional paid-in capital         $ 9,400,000  
0.25% Convertible Senior Notes Due 2022 [Member] | Common Stock [Member]            
Debt Instrument [Line Items]            
Warrants holders option to purchase number of shares of company’s common stock | shares         4,200 4,200
Warrants exercise price per share | $ / shares         $ 115.80  
0.25% Convertible Senior Notes Due 2022 [Member] | Liability Component [Member]            
Debt Instrument [Line Items]            
Debt issuance costs   7,900,000        
0.25% Convertible Senior Notes Due 2022 [Member] | Equity Component [Member]            
Debt Instrument [Line Items]            
Debt issuance costs   $ 2,900,000        
0.25% Convertible Senior Notes Due 2022 [Member] | Minimum [Member]            
Debt Instrument [Line Items]            
Debt instrument, conversion price per share | $ / shares         94.77  
Percentage of closing price to trigger debt conversion   130.00% 130.00%      
0.25% Convertible Senior Notes Due 2022 [Member] | Maximum [Member]            
Debt Instrument [Line Items]            
Debt instrument, conversion price per share | $ / shares         $ 115.83  
Percentage of closing price to trigger debt conversion   98.00%        
0.25% Convertible Senior Notes Due 2022 [Member] | Scenario 1 [Member]            
Debt Instrument [Line Items]            
Debt instrument, convertible, threshold trading days | d   20        
Debt instrument, convertible, threshold consecutive trading days | d   30        
0.25% Convertible Senior Notes Due 2022 [Member] | Scenario Two [Member]            
Debt Instrument [Line Items]            
Debt instrument, convertible, threshold trading days | d   5        
Debt instrument, convertible, threshold consecutive trading days | d   5        
0.25% Convertible Senior Notes Due 2022 [Member] | Private Offering [Member]            
Debt Instrument [Line Items]            
Principal amount of long term debt   $ 350,000,000        
0.25% Convertible Senior Notes Due 2022 [Member] | Over-Allotment Options [Member]            
Debt Instrument [Line Items]            
Principal amount of long term debt   $ 50,000,000