v3.7.0.1
Pension Plans Narrative (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]        
Compensation expense recognized for 401(k)   $ 50.0 $ 26.0 $ 24.0
NAV Per Share, Investment Redemption, Notice Period   90 days    
Foreign Pension Plan [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Unrecognized prior service credits, before tax   $ 0.2    
Unrecognized prior service credits, after tax   0.2    
Unrecognized actuarial losses, before tax   97.0    
Unrecognized actuarial losses, after tax   74.0    
Prior service credits, before tax   0.1    
Prior service credits, after tax   0.1    
Future actuarial losses, before tax   4.0    
Future actuarial losses, after tax   $ 3.0    
Expected long-term return on plan assets   4.19% 4.30%  
Employer contributions   $ 10.7 $ 10.8  
Foreign Pension Plan [Member] | Scenario, Forecast [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Expected contributions $ 10.0      
Minimum [Member] | Foreign Pension Plan [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Expected long-term return on plan assets   1.75% 2.25%  
Maximum [Member] | Foreign Pension Plan [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Expected long-term return on plan assets   6.00% 6.00%