Share-Based Incentive Compensation (details) - Original and Reload Grants (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010 years	Dec. 31, 2009 years
Original grants [Member]
Information regarding original and reload grants [Line Items]
Expected term of stock options (in years)	6	6	6
Expected volatility rate of the Company's stock	28.0%-28.6%	28.3%-29.1%	28.2%-34.1%
Weighted average volatility (percent)	28.20%	28.40%	32.40%
Expected annual dividend per share	$1.44 - $1.64	$1.32 - $1.44	$1.20 - $1.32
Risk-free rate	1.19%-2.62%	1.68%-2.71%	2.07%-2.85%
Stock options granted, number	2,380,199
Stock options granted, weighted average exercise price	$ 56.85
Stock options granted, weighted average grant-date fair value of options granted (per share)	$ 12.94	$ 11.94	$ 9.54
Total intrinsic value of options exercised during the year	$ 76	$ 77	$ 52
Term of share-based compensation awards	Stock option awards granted to eligible officers and key employees have a ten-year term. The stock options granted generally vest upon meeting certain years of service criteria. Except as the Compensation Committee of the Board may allow in the future, stock options cannot be sold or transferred by the participant. The stock options granted under the 2004 Incentive Plan vest three years after grant date (cliff vest).
Reload grants [Member]
Information regarding original and reload grants [Line Items]
Expected term of stock options		1-2 years	1-2 years
Expected term of stock options (in years)	1
Expected volatility rate of the Company's stock	15.7%-17.6%	18.3%-41.6%	36.5%-55.1%
Weighted average volatility (percent)	15.90%	21.10%	42.90%
Expected annual dividend per share	$1.44 - $1.64	$1.32 - $1.44	$1.20 - $1.32
Risk-free rate	0.10%-0.29%	0.20%-0.95%	0.29%-1.21%
Stock options granted, number	574,815
Stock options granted, weighted average exercise price	$ 62.25
Stock options granted, weighted average grant-date fair value of options granted (per share)	$ 3.19	$ 3.46	$ 8.95
Total intrinsic value of options exercised during the year	$ 11	$ 3
Term of share-based compensation awards	The reload option is permitted on certain stock option awards granted prior to January 2003 at an amount equal to the number of shares of the common stock used to satisfy both the exercise price and withholding taxes due upon exercise of an option and vest either six months or one year after the grant date and are exercisable for the remaining term of the related original option.