Annual report pursuant to Section 13 and 15(d)

Acquired Intangible Assets Fair Value and Weighted-Average Useful Life (Detail)

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Acquired Intangible Assets Fair Value and Weighted-Average Useful Life (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Year
Dec. 31, 2010
Year
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]    
Identifiable intangible assets $ 52.2 [1] $ 30.6 [1]
Weighted-average useful life 6.9 6.8
Customer relationships
    
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]    
Identifiable intangible assets 29.9 11.5
Weighted-average useful life 8.8 8.9
Acquired software and technology
    
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]    
Identifiable intangible assets 13.4 13.9
Weighted-average useful life 4.2 5.9
Purchased data files
    
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]    
Identifiable intangible assets 3.2  
Weighted-average useful life 5.2  
Non-compete agreements
    
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]    
Identifiable intangible assets 2.3 3.8
Weighted-average useful life 3.7 3.7
Trade names and other intangible assets
    
Schedule of Business Acquisitions, Purchase Price Allocation [Line Items]    
Identifiable intangible assets $ 3.4 $ 1.4
Weighted-average useful life 5.5 5.8
[1] Identifiable intangible assets are further disaggregated in the following table.