Capital Stock - Net Income Per Common Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share [Abstract]
Income attributable to common stock	$ 698	$ 778
Mandatory Convertible Preferred Stock	19	19
Income attributable to common stock, including assumed conversions	$ 717	$ 797
Income attributable to common stock, shares	392	385
Mandatory Convertible Preferred Stock	14	12
Stock options and other	2	2
Income attributable to common stock, including assumed conversions, shares	408	399
Income attributable to common stock, per share	$ 1.78	$ 2.02
Income attributable to common stock, including assumed conversions, per share	$ 1.76	$ 2.00