Capital Stock and Stock-Based Compensation Plans (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010 years	Dec. 31, 2009 years	Dec. 31, 1989	Dec. 29, 2010
Preference Stock [Abstract]
Shares authorized (in shares)	50,000,000
Series B Convertible Preference stock (in shares)				6,315,149
Common Stock Shares Converted From One Share Of Preferred Stock				8
Redemption price (in dollars per share)				$ 65
Minimum cumulative dividend rate for Convertible Preference stock (in dollars per share)				$ 2.44
Preference stock retired (in shares)					2,405,192
Common stock converted (in shares)					19,241,536
Common stock outstanding and issued to Employee Stock Ownership Plan (in shares)	17,102,005	19,225,073
Stock Repurchases [Abstract]
Repurchased stock	$ 1,806	$ 2,020	$ 1,063
Summary of common stock activity [Roll Forward]
Common Stock Balance, January 1 (in shares)	494,850,467	494,165,017	501,412,580
Common stock acquired (in shares)	(21,320,936)	(25,401,785)	(14,916,340)
Shares issued for stock options (in shares)	5,758,879	4,233,775	5,455,317
Shares issued for restricted stock and other (in shares)	729,665	993,132	800,388
Preference stock conversion (in shares)		20,860,328	1,413,072
Common Stock Balance, December 31 (in shares)	480,018,075	494,850,467	494,165,017
Summary Of Treasury Stock Activity [Roll Forward]
Treasury Stock Balance, January 1 (in shares)	238,002,713	238,688,163	231,440,600
Common stock acquired (in shares)	21,320,936	25,401,785	14,916,340
Shares issued for stock options (in shares)	(5,758,879)	(4,233,775)	(5,455,317)
Shares issued for restricted stock and other (in shares)	(729,665)	(993,132)	(800,388)
Preference stock conversion (in shares)		(20,860,328)	(1,413,072)
Treasury Stock Balance, December 31 (in shares)	252,835,105	238,002,713	238,688,163
Stock-based compensation [Abstract]
Allocated Share-based Compensation Expense	122	121	117
Total income tax benefit	40	40	40
Fair Value Assumptions [Abstract]
Weighted-average estimated fair value of stock options granted (in dollars per share)	$ 11.93	$ 11.00	$ 12.06
Expected term (in years)	4.5	4.5	4.5
Expected Volatility Rate (in hundredths)	21.30%	22.50%	22.10%
Risk-Free Rate (in hundredths)	0.80%	1.30%	2.30%
Expected Dividend Yield (in hundredths)	2.60%	2.80%	2.40%
Summary of restricted stock award activity [Roll Forward]
Restricted stock awards - beginning balance (in shares)	2,777,000
Granted (in shares)	986,000
Vested (in shares)	(690,000)
Forfeited (in shares)	(36,000)
Restricted stock awards - ending balance (in shares)	3,037,000	2,777,000
Additional disclosures pertaining to restricted stock awards [Abstract]
Weighted average grant date fair value of restricted stock awards - beginning of period (in dollars per share)	$ 73
Weighted average grant date fair value of restricted stock awards - shares granted (in dollars per share)	$ 84
Weighted average grant date fair value of restricted stock awards - shares vested (in dollars per share)	$ 76
Weighted average grant date fair value of restricted stock awards - shares forfeited (in dollars per share)	$ 71
Weighted average grant date fair value of restricted stock awards - end of period (in dollars per share)	$ 76	$ 73
Summary of stock option plan activity [Roll Forward]
Options - beginning balance (in shares)	24,517,000
Granted (in shares)	4,841,000
Shares issued for stock options (in shares)	(6,846,000)
Forfeited or expired (in shares)	(218,000)
Options - ending balance (in shares)	22,294,000	24,517,000
Options exercisable (in shares)	13,121,000
Additional disclosures pertaining to stock options [Abstract]
Weighted average exercise price of options - beginning of period (in dollars per share)	$ 69
Weighted average exercise price of options - shares granted (in dollars per share)	$ 90
Weighted average exercise price of options - shares exercised (in dollars per share)	$ 62
Weighted average exercise price of options - shares forfeited or expired (in dollars per share)	$ 78
Weighted average exercise price of options - end of period (in dollars per share)	$ 76	$ 69
Weighted average exercise price of options exercisable - end of period (in dollars per share)	$ 71
Weighted average remaining contractual life, options outstanding (in years)	4
Weighted average remaining contractual life, options exercisable (in years)	3
Value of unexercised in-the-money options, options outstanding	360
Value of unexercised in-the-money options, options exercisable	276
Stock-based compensation, additional disclosures [Abstract]
Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options	32	31	16
Proceeds from Stock Options Exercised	332	211	284
Program 2010 [Member]
Stock Repurchases [Abstract]
Treasury stock repurchase authorization (in shares)		40,000,000
Program 2011 [Member]
Stock Repurchases [Abstract]
Treasury stock repurchase authorization (in shares)	50,000,000
Incentive Stock Plans [Member]
Additional disclosures pertaining to restricted stock awards [Abstract]
Number of shares available for grant (in shares)	9,310,000
Unrecognized compensation expense	65
Unrecognized compensation expense, weighted-average period of recognition in years	2.2
Total fair value of shares vested	50	69	48
Stock-based compensation, additional disclosures [Abstract]
Vesting period (in years)	3 years
Stock Option Plans [Member]
Additional disclosures pertaining to restricted stock awards [Abstract]
Number of shares available for grant (in shares)	9,092,000
Unrecognized compensation expense	40
Unrecognized compensation expense, weighted-average period of recognition in years	1.5
Stock-based compensation, additional disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 162	$ 133	$ 120
Contractual term (in years)	6 years
Vesting period (in years)	3 years