Quarterly report pursuant to Section 13 or 15(d)

Shareholders' Deficit - Additional Information (Detail)

v3.10.0.1
Shareholders' Deficit - Additional Information (Detail)
$ / shares in Units, $ in Millions
 1 Months Ended 3 Months Ended 6 Months Ended 12 Months Ended
Apr. 24, 2018
May 31, 2018
USD ($)
$ / shares
shares
Feb. 28, 2014
USD ($)
$ / shares
shares
Jun. 30, 2018
USD ($)
$ / shares
shares
Mar. 31, 2018
USD ($)
$ / shares
shares
Jun. 30, 2017
USD ($)
$ / shares
shares
Mar. 31, 2017
USD ($)
$ / shares
shares
Mar. 31, 2014
USD ($)
Jun. 30, 2018
USD ($)
$ / shares
shares
Jun. 30, 2017
USD ($)
Dec. 31, 2017
USD ($)
shares
Dec. 31, 2016
USD ($)
Oct. 31, 2017
USD ($)
Feb. 21, 2017
USD ($)
Stockholders Equity [Line Items]                            
Share repurchase program authorized amount       $ 1,500.0         $ 1,500.0         $ 1,500.0
Share repurchase program, remaining authorized capacity       113.3         $ 113.3     $ 233.0    
Share repurchase program expiration date                 Feb. 21, 2020     Jun. 30, 2017    
Forward transactions, shares to be purchased | shares                 19.9          
Accumulated deficit       $ (646.4)         $ (646.4)   $ (248.1)      
Repurchase of common stock, value                 $ 681.4 $ 286.2        
Treasury stock shares, at cost | shares       10,000,000         10,000,000   10,000,000      
Shares repurchases, value                 $ 600.7 240.5 $ 4.2      
Withheld for tax purpose for share-based compensation plans                 80.7 45.7        
Payments for share repurchases                 685.6 273.6        
Share repurchases for which subsequent payment to be made           $ 12.6       12.6        
Stock split conversion ratio 2   2                      
Terminating result of portion of capped call transactions cash received                 55.9          
Other comprehensive income (loss) before foreign currency translation adjustments reclassifications, Tax expense (benefit)       $ (3.1)   2.7     (2.0) 5.3        
Convertible Senior Notes Due 2019 [Member]                            
Stockholders Equity [Line Items]                            
Stock split conversion ratio     2                      
Capped call transactions [Member]                            
Stockholders Equity [Line Items]                            
Capped call transactions with financial institutions     $ 123.8                      
Capped call transactions price per common share | $ / shares     $ 60.39                      
Increase (decrease) in additional paid-in capital, other               $ (123.8)            
Terminating result of portion of capped call transactions cash received                 $ 55.9          
Capped call transactions [Member] | Common Share [Member]                            
Stockholders Equity [Line Items]                            
Weighted-average adjusted cap price per common share | $ / shares       54.44         54.44          
Capped call transactions [Member] | Convertible Senior Notes Due 2019 [Member]                            
Stockholders Equity [Line Items]                            
Convertible notes conversion price | $ / shares     $ 43.14                      
Prepaid forward share repurchase transactions [Member]                            
Stockholders Equity [Line Items]                            
Forward share repurchase transactions amount     $ 685.8         685.8            
Forward transactions, shares to be purchased | shares     19,900,000                      
Average cost per share of shares repurchased | $ / shares     $ 34.51                      
Settlement date of forward transactions                 Aug. 15, 2019          
Forward counterparties shares purchased and subsequently retired | shares       8,400,000                    
Non-cash interest expense relating to unamortized non-cash issuance costs       $ 3.1                    
Shares outstanding under forward purchasing transactions | shares       11,500,000         11,500,000          
Accumulated deficit               (653.9)            
Additional paid-in-capital               (31.9)            
Non-cash forward transaction issuance costs               $ 35.8            
Non-cash interest expense relating to amortization of non-cash issuance costs       $ 4.7   $ 1.6     $ 6.3 $ 3.2        
Open market purchases [Member] | Indirect wholly owned subsidiary [Member]                            
Stockholders Equity [Line Items]                            
Average cost per share of shares repurchased | $ / shares         $ 33.90 $ 33.53 $ 28.05              
Repurchase of common stock, shares | shares       0 8,400 5,300,000 2,200,000              
Repurchase of common stock, value         $ 0.3 $ 179.8 $ 60.7              
May 2018 Dutch Auction Tender Offer [Member]                            
Stockholders Equity [Line Items]                            
Average cost per share of shares repurchased | $ / shares   $ 52.50                        
Repurchase of common stock, shares | shares   11,400,000                        
Repurchase of common stock, value   $ 600.0                        
October 2017 Dutch Auction Tender Offer [Member]                            
Stockholders Equity [Line Items]                            
Forward share repurchase transactions amount                 $ 1.6          
Contingent value right agreement term                 2 years          
Non-transferable contractual contingent value right agreement initial fair value                         $ 7.3  
CVR expiration period                 2019-08          
Loss recognized in other expense       $ 4.7         $ 16.0          
Non-transferable contractual contingent value right agreement change in fair value       $ 22.9         $ 22.9   $ 6.9