XML 71 R58.htm IDEA: XBRL DOCUMENT v3.10.0.1
Intangible Assets - Carrying Amount of Goodwill Allocated by Domestic and Foreign Operations (Detail) - USD ($)
$ in Millions
Sep. 30, 2018
Dec. 31, 2017
Goodwill [Line Items]    
Total goodwill - net $ 4,501.3 $ 4,164.8 [1]
Unites States [Member]    
Goodwill [Line Items]    
Total goodwill - net 2,656.3 2,306.7
United Kingdom [Member]    
Goodwill [Line Items]    
Total goodwill - net 733.7 745.7
Canada [Member]    
Goodwill [Line Items]    
Total goodwill - net 373.2 374.0
Australia [Member]    
Goodwill [Line Items]    
Total goodwill - net 411.8 416.6
New Zealand [Member]    
Goodwill [Line Items]    
Total goodwill - net 207.5 218.9
Other Foreign [Member]    
Goodwill [Line Items]    
Total goodwill - net 118.8 102.9
Brokerage [Member]    
Goodwill [Line Items]    
Total goodwill - net 4,452.0 4,119.2
Brokerage [Member] | Unites States [Member]    
Goodwill [Line Items]    
Total goodwill - net 2,626.7 2,280.9
Brokerage [Member] | United Kingdom [Member]    
Goodwill [Line Items]    
Total goodwill - net 726.7 738.5
Brokerage [Member] | Canada [Member]    
Goodwill [Line Items]    
Total goodwill - net 373.2 374.0
Brokerage [Member] | Australia [Member]    
Goodwill [Line Items]    
Total goodwill - net 411.8 416.6
Brokerage [Member] | New Zealand [Member]    
Goodwill [Line Items]    
Total goodwill - net 197.4 209.3
Brokerage [Member] | Other Foreign [Member]    
Goodwill [Line Items]    
Total goodwill - net 116.2 99.9
Risk Management [Member]    
Goodwill [Line Items]    
Total goodwill - net 46.7 42.6
Risk Management [Member] | Unites States [Member]    
Goodwill [Line Items]    
Total goodwill - net 29.6 25.8
Risk Management [Member] | United Kingdom [Member]    
Goodwill [Line Items]    
Total goodwill - net 7.0 7.2
Risk Management [Member] | New Zealand [Member]    
Goodwill [Line Items]    
Total goodwill - net 10.1 9.6
Corporate [Member]    
Goodwill [Line Items]    
Total goodwill - net 2.6 3.0
Corporate [Member] | Other Foreign [Member]    
Goodwill [Line Items]    
Total goodwill - net $ 2.6 $ 3.0
[1] See Note 3 - Revenues from Contracts with Customers for additional information about the restatements related to Topic 606.