Capital Stock - Net Income Per Common Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Income attributable to common stock	$ 300	$ 161	$ 2,014	$ 1,276
Mandatory Convertible Preferred Stock			44
Income attributable to common stock, including assumed conversions	$ 300	$ 161	$ 2,058	$ 1,276
Income attributable to common stock, shares	399	391	394	388
Mandatory Convertible Preferred Stock			11
Stock options and other	2	2	2	2
Income attributable to common stock, including assumed conversions, shares	401	393	407	390
Income attributable to common stock, per share	$ 0.75	$ 0.41	$ 5.11	$ 3.29
Income attributable to common stock, including assumed conversions, per share	$ 0.75	$ 0.41	$ 5.06	$ 3.27