XML 65 R53.htm IDEA: XBRL DOCUMENT v3.8.0.1
Business Combinations - Additional Information (Detail)
 3 Months Ended 195 Months Ended
Mar. 31, 2018
USD ($)
Entity
Mar. 31, 2017
USD ($)
Entity
Mar. 31, 2018
USD ($)
Entity
Business Acquisition [Line Items]      
Accretion of the discount on acquisition $ 5,100,000 $ 5,100,000  
Expense related to net adjustments to estimated fair value of liability for earnout obligations $ 2,300,000 $ 6,700,000  
Number of companies acquired | Entity 39 40 466
Aggregate amount of maximum earnout obligations related to acquisitions $ 571,000,000    
Aggregate amount of maximum earnout obligations related to acquisitions, recorded in consolidated balance sheet 270,900,000    
Goodwill 41,000,000   $ 41,000,000
Expiration lists 46,200,000   46,200,000
Non-compete agreements 400,000   400,000
Total revenues related to acquisitions in the aggregate 1,839,500,000 $ 1,653,700,000  
Brokerage and Risk Management [Member]      
Business Acquisition [Line Items]      
Goodwill 41,000,000   41,000,000
Expiration lists 46,200,000   46,200,000
Non-compete agreements $ 400,000   400,000
Expiration Lists [Member] | Minimum [Member]      
Business Acquisition [Line Items]      
Estimated useful lives of intangibles assets, years   2 years  
Expiration Lists [Member] | Maximum [Member]      
Business Acquisition [Line Items]      
Estimated useful lives of intangibles assets, years   15 years  
Non-Compete Agreements [Member] | Minimum [Member]      
Business Acquisition [Line Items]      
Estimated useful lives of intangibles assets, years   2 years  
Non-Compete Agreements [Member] | Maximum [Member]      
Business Acquisition [Line Items]      
Estimated useful lives of intangibles assets, years   5 years  
Trade Names [Member] | Minimum [Member]      
Business Acquisition [Line Items]      
Estimated useful lives of intangibles assets, years   2 years  
Trade Names [Member] | Maximum [Member]      
Business Acquisition [Line Items]      
Estimated useful lives of intangibles assets, years   15 years  
2018 Acquisitions [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]      
Business Acquisition [Line Items]      
Revenue growth rate 0.05%    
Discount rate 0.08%    
2018 Acquisitions [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]      
Business Acquisition [Line Items]      
Revenue growth rate 0.15%    
Discount rate 0.095%    
2017 Acquisitions [Member] | Income Approach Valuation Technique [Member] | Minimum [Member]      
Business Acquisition [Line Items]      
Revenue growth rate 3.00%    
Discount rate 12.00%    
Attrition rate 5.00%    
2017 Acquisitions [Member] | Income Approach Valuation Technique [Member] | Maximum [Member]      
Business Acquisition [Line Items]      
Revenue growth rate 3.50%    
Discount rate 14.00%    
Attrition rate 10.00%    
Business Acquisition [Member]      
Business Acquisition [Line Items]      
Annualized revenue of business acquisitions $ 29,900,000    
Total revenues related to acquisitions in the aggregate 6,200,000    
Net earnings 600,000    
Business Acquisition [Member] | Brokerage [Member]      
Business Acquisition [Line Items]      
Expiration lists 46,200,000   46,200,000
Non-compete agreements 400,000   400,000
Deferred tax liability 1,800,000   1,800,000
Goodwill related to nondeductible amortizable intangible assets 1,800,000    
Business Acquisition [Member] | Expiration Lists [Member] | Brokerage [Member]      
Business Acquisition [Line Items]      
Business acquisition not deductible for income tax purposes 6,300,000   6,300,000
Business Acquisition [Member] | Non-Compete Agreements [Member] | Brokerage [Member]      
Business Acquisition [Line Items]      
Business acquisition not deductible for income tax purposes $ 100,000   $ 100,000