Quarterly report pursuant to Section 13 or 15(d)

Debt - Additional Information (Detail)

v2.4.0.6
Debt - Additional Information (Detail) (USD $)
3 Months Ended
Mar. 31, 2013
Debt Instrument [Line Items]  
Credit facility borrowing capacity 750,000,000
Credit facility expiration date 2017-12
Line of credit facility, potential maximum borrowing capacity 1,000,000,000
Line of credit facility, available for borrowing 588,600,000
Commercial paper notes 750,000,000
Commercial Paper Notes Outstanding 160,000,000
Minimum [Member]
 
Debt Instrument [Line Items]  
Commercial paper, maturity date 1 day
Maximum [Member]
 
Debt Instrument [Line Items]  
Commercial paper, maturity date 397 days