Goodwill And Intangible Assets - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization expense	$ 54		$ 58	$ 163	$ 172
Estimated amortization expense for each of the next five years				216
Impairment charge		$ 20		$ 20
Weighted Average
Goodwill and Intangible Assets Disclosure [Line Items]
Life of our amortizable intangible assets (in years)				13 years 2 months 12 days