Quarterly report pursuant to Section 13 or 15(d)

Shareholders' Deficit - Additional Information (Detail)

v3.19.2
Shareholders' Deficit - Additional Information (Detail)
$ / shares in Units, $ in Millions
 1 Months Ended 3 Months Ended 6 Months Ended 12 Months Ended
Oct. 30, 2018
USD ($)
Feb. 28, 2014
USD ($)
$ / shares
shares
Jun. 30, 2019
USD ($)
$ / shares
shares
Dec. 31, 2018
USD ($)
Day
shares
Jun. 30, 2018
USD ($)
shares
Mar. 31, 2014
USD ($)
Jun. 30, 2019
USD ($)
Day
$ / shares
shares
Jun. 30, 2018
USD ($)
$ / shares
shares
Dec. 31, 2018
USD ($)
shares
Oct. 31, 2017
USD ($)
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   1,500.0       $ 1,500.0      
Share repurchase program expiration date Feb. 21, 2020           Oct. 30, 2023      
Forward counterparties shares purchased and subsequently retired | shares         8,400,000   2,000,000.0 8,400,000    
Accumulated deficit     $ (353.5) $ (526.3)     $ (353.5)   $ (526.3)  
Repurchase of common stock, shares | shares     100,000   12,000,000.0   200,000 13,100,000    
Treasury stock shares, at cost | shares     10,000,000.0 10,000,000.0     10,000,000.0   10,000,000.0  
Shares repurchases, inclusive of transaction costs and issuance of CVR value             $ 0.0 $ 600.7    
Withheld for tax purpose for share-based compensation plans             9.0 80.7    
Shares repurchases, value     $ 1.4   $ 631.5   9.0 681.4    
Payments for share repurchases             9.0 685.6    
Payments for share repurchases from prior period liability               4.2    
Terminating result of portion of capped call transactions cash received               55.9    
Other comprehensive (loss) income before foreign currency translation adjustments reclassifications, tax expense (benefit)     $ (1.5)   $ (3.1)   $ (1.0) $ (2.0)    
Convertible Senior Notes Due 2019 [Member]                    
Stockholders Equity [Line Items]                    
Convertible notes conversion price | $ / shares   $ 43.14 $ 43.06       $ 43.06      
Minimum percentage of common share price over conversion price for conversion   130.00%   130.00%            
Convertible notes, number of trading days of threshold limit (whether or not consecutive) | Day       20     20      
Convertible notes, number of trading days of threshold limit in consecutive days | Day       30     30      
Reclassification of difference between aggregate principal amount and carrying value from additional paid in capital to temporary equity       $ 11.3            
Convertible notes maturity   Aug. 15, 2019         Aug. 15, 2019      
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] | Convertible Senior Notes Due 2019 [Member]                    
Stockholders Equity [Line Items]                    
Convertible notes conversion price | $ / shares   $ 43.14                
Capped call transactions [Member] | Common Shares [Member]                    
Stockholders Equity [Line Items]                    
Weighted-average adjusted cap price per common share | $ / shares     53.37       53.37      
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     0   8,400,000   2,000,000.0 8,400,000    
Non-cash interest expense relating to unamortized non-cash issuance costs         $ 3.1   $ 0.2 $ 3.1    
Shares outstanding under forward purchasing transactions | shares     4,000,000.0       4,000,000.0      
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     $ 0.3   $ 4.7   $ 1.0 $ 6.3    
Open market purchases [Member]                    
Stockholders Equity [Line Items]                    
Repurchase of common stock, shares | shares     0   0   0 0    
Open market purchases [Member] | Indirect wholly owned subsidiary [Member]                    
Stockholders Equity [Line Items]                    
Average cost per share of shares repurchased | $ / shares               $ 33.90    
Repurchase of common stock, shares | shares               8,400    
Repurchase of common stock, value               $ 0.3    
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      
Gain (loss) recognized in other (income) expense     $ 5.9   $ (4.7)   $ 14.4 $ (16.0)    
Non-transferable contractual contingent value right agreement change in fair value     $ 1.3 $ 15.7     $ 1.3   $ 15.7