XML 67 R49.htm IDEA: XBRL DOCUMENT v3.8.0.1
Summary of Significant Accounting Policies - Property and Equipment (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Property, Plant and Equipment [Line Items]    
Property and equipment $ 633.4 $ 567.0
Land    
Property, Plant and Equipment [Line Items]    
Property and equipment 3.4 5.5
Buildings    
Property, Plant and Equipment [Line Items]    
Property and equipment $ 14.5 16.2
Buildings | Maximum    
Property, Plant and Equipment [Line Items]    
Estimated useful lives 40 years  
Furniture, fixtures, and autos    
Property, Plant and Equipment [Line Items]    
Property and equipment $ 172.3 157.6
Furniture, fixtures, and autos | Minimum    
Property, Plant and Equipment [Line Items]    
Estimated useful lives 2 years  
Furniture, fixtures, and autos | Maximum    
Property, Plant and Equipment [Line Items]    
Estimated useful lives 15 years  
Computer equipment    
Property, Plant and Equipment [Line Items]    
Property and equipment $ 137.1 117.8
Computer equipment | Minimum    
Property, Plant and Equipment [Line Items]    
Estimated useful lives 2 years  
Computer equipment | Maximum    
Property, Plant and Equipment [Line Items]    
Estimated useful lives 15 years  
Leasehold improvements    
Property, Plant and Equipment [Line Items]    
Property and equipment $ 306.1 $ 269.9