Quarterly report pursuant to Section 13 or 15(d)

Commitments and Contingencies - Additional Information (Detail)

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Commitments and Contingencies - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
 9 Months Ended
Sep. 30, 2012
Dec. 31, 2011
Commitments and Contingencies Disclosure [Line Items]    
Agreement With Computer Sciences Corporation, expiration date Jul. 31, 2018  
Agreement With Computer Sciences Corporation, renewable period 10 years  
Agreement With Computer Sciences Corporation, option to sell its credit reporting business, option expiration date Aug. 01, 2013  
Agreement With Computer Sciences Corporation, option to buy CSC credit reporting business exercise expected payment period The option exercise price will be determined by a third-party appraisal process and would be due in cash within 180 days after the exercise of the option.  
Performance bonds and standby letters of credit remaining maturity date One year or less  
Reduction In Aggregate Minimum Contractual Obligation $ 15  
Minimum [Member]
    
Commitments and Contingencies Disclosure [Line Items]    
Data Processing, Outsourcing Services And Other Agreements, expiration year 2012  
Data Processing, Outsourcing Services And Other Agreements, estimated aggregate contractual obligation   70
Agreement With Computer Sciences Corporation, estimated option exercise price 750  
Maximum [Member]
    
Commitments and Contingencies Disclosure [Line Items]    
Data Processing, Outsourcing Services And Other Agreements, expiration year 2018  
Data Processing, Outsourcing Services And Other Agreements, expected future year's minimum contractual obligation   30
Agreement With Computer Sciences Corporation, estimated option exercise price $ 1,000