Debt - Additional Information (Detail) (USD $)		1 Months Ended			3 Months Ended		9 Months Ended	1 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Jun. 30, 2012 Secured Debt	Sep. 30, 2012 Secured Debt	Jul. 31, 2012 Secured Debt Repayment of Debt	Sep. 30, 2012 LIBOR Plus A Margin Of 138 Basis Points	Mar. 31, 2012 LIBOR Plus A Margin Of 138 Basis Points	Sep. 30, 2012 LIBOR Plus A Margin Of 138 Basis Points	Oct. 31, 2012 LIBOR Plus A Margin Of 138 Basis Points Repayment of Debt	Mar. 31, 2012 LIBOR Plus A Margin Of 175 Basis Points	Sep. 30, 2012 LIBOR Plus A Margin Of 175 Basis Points
Debt Disclosure [Line Items]
Term loan						$ 1,200,000,000			$ 200,000,000
Maturity date							Dec. 31, 2017			Dec. 31, 2017
Base points margin			0.70%			1.38%			1.75%
Term loan issued, payments made					1,000,000,000			200,000,000
Receivable securitization facility, borrowed amount		225,000,000
Receivable securitization facility, interest rate			0.224%
Receivable securitization facility, repaid date				2012-07
Debt and capital lease obligations	10,500,000,000
Debt fair value	$ 12,500,000,000