Quarterly report pursuant to Section 13 or 15(d)

Income Taxes - Additional Information (Detail)

v3.8.0.1
Income Taxes - Additional Information (Detail) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Income Taxes [Line Items]        
Income taxes (benefit) expense $ 26.4 $ 41.7 $ 84.2 $ 69.2
Effective income tax rate 32.60% 32.20% 23.30% 30.10%
Total amount of unrecognized tax benefits, including related interest and penalties $ 74.2   $ 74.2  
Unrecognized tax benefits excluding interest and penalties that if recognized would affect the effective tax rate 53.1   53.1  
Total accrued interest for tax contingencies 12.0   12.0  
Total accrued penalties for tax contingencies 2.5   2.5  
Amount of unrecognized tax benefits that could decrease within the next 12 months 8.8   8.8  
Decrease in unrecognized tax benefits due to the settlement of audits or resolution of administrative or judicial proceedings 3.7   3.7  
Decrease in unrecognized tax benefits expiration of statute of limitations 5.1   5.1  
Accounting Standards Update 2016-09 [Member]        
Income Taxes [Line Items]        
Excess tax benefits included in discrete events $ 0.6   $ 26.4