Shareholders' Equity and Stock Incentive Plans, Stock Incentive Plans (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation cost	$ 198	$ 158	$ 143
Tax benefit	(61)	(50)	(46)
Stock-based compensation cost, net of tax	137	108	97
Number of shares reserved for issuance to recipient (in shares)	133,000,000
Number of shares available for future grants (in shares)	14,000,000
Fair value assumptions and methodology [Abstract]
Number of shares of restricted stock issued to non-employee directors (in shares)	19,395
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Quarter of the year that stock options are generally issued	second
Vesting period of stock options to employees - minimum (in years)	3
Vesting period of stock options to employees - maximum (in years)	4
Expiration from the grant date of the award (in years)	10
Share-based payment award, options, outstanding [Roll Forward]
Outstanding at beginning of period (in shares)	15,800,000
Granted (in shares)	3,400,000
Exercised (in shares)	(3,900,000)
Forfeited/expired (in shares)	(400,000)
Outstanding at end of period (in shares)	14,900,000	15,800,000
Share based payment award, options, additional disclosures [Abstract]
Outstanding, weighted average exercise price - beginning of period (in dollars per share)	$ 26.79
Granted, Weighted average exercise price (in dollars per share)	$ 43.87
Exercised, weighted average exercise price (in dollars per share)	$ 22.05
Forfeited/expired, weighted average exercise price (in dollars per share)	$ 33.54
Outstanding , weighted average exercise price - end of period (in dollars per share)	$ 31.74	$ 26.79
Weighted average remaining contractual term at end of period (in years)	6.7
Aggregate intrinsic value options outstanding end of period	94
Number of shares exercisable at period end (in shares)	8,500,000
Weighted average exercise price - exercisable at period end (in dollars per share)	$ 29.07
Weighted average remaining contractual term - exercisable at period end (in years)	5.3
Aggregate intrinsic value - exercisable at period end	68
Intrinsic value of options exercised during the period	102	38	10
Employee service share based compensation, aggregate disclosures [Abstract]
Unrecognized compensation cost - nonvested awards at period end	55
Weighted average period unrecognized compensation cost is to be recognized (in years)	2
Cash received from option exercises	160	102	74
Fair value assumptions and methodology [Abstract]
Expected term (in years)	5.20	5.27	5.18
Expected volatility (in hundredths)	40.00%	40.00%	53.00%
Expected dividend yield - minimum (in hundredths)	0.69%	0.99%	1.23%
Expected dividend yield - maximum (in hundredths)	1.01%	1.71%	2.55%
Risk-free interest rate - minimum (in hundredths)	0.93%	1.20%	1.38%
Risk-free interest rate - maximum (in hundredths)	2.29%	2.78%	2.47%
Weighted average grant-date fair value per share (in dollars per share)	$ 15.61	$ 9.94	$ 9.36
Restricted stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration from the grant date of the award (in years)	10
Employee service share based compensation, aggregate disclosures [Abstract]
Unrecognized compensation cost - nonvested awards at period end	352
Weighted average period unrecognized compensation cost is to be recognized (in years)	4
Equity instruments other than options, nonvested [Roll Forward]
Nonvested shares - beginning balance (in shares)	13,300,000
Granted (in shares)	5,400,000
Vested (in shares)	(3,700,000)
Forfeited (in shares)	(800,000)
Nonvested shares - ending balance (in shares)	14,200,000	13,300,000
Equity instruments other than options, nonvested, additional disclosures [Abstract]
Nonvested shares outstanding, weighted average grant date fair value - beginning balance (in dollars per share)	$ 28.10
Granted, weighted average grant date fair value (in dollars per share)	$ 43.35	$ 29.39	$ 22.90
Vested, weighted average grant date fair value in dollars per share)	$ 28.81
Forfeited, weighted average grant date fair value (in dollars per share)	$ 32.59
Nonvested shares outstanding, weighted average grant date fair value - ending balance (in dollars per share)	$ 33.45	$ 28.10
Total fair value of shares vested during the period	$ 165	$ 100	$ 59
Restricted stock [Member] | Non-Employee Directors [Member]
Share-based Goods and Nonemployee Services Transaction [Line Items]
Vesting period, description	Minimum restriction period of six months, and the restrictions lapse upon the earlier of mandatory director retirement at age 72 or early retirement from the Board after four years of service.
Number of units the plan allows for annual award for nonemployee directors (in shares)	800
The time over which the fair market value of the stock is amortized for awards awarded to nonemployee directors	The lesser of the time from the grant date to age 72 or the time from the grant date to completion of four years of service on the Board.
Number of shares of common stock reserved for issuance to nonemployee directors (in shares)	200,000
Number of shares issued to non-employee directors inception-to-date (in shares)	145,600
Number of shares issued to non-employee directors during the period (in shares)	7,200	8,000	8,000
Employee stock purchase plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for issuance to recipient (in shares)	44,000,000
Employee Stock Purchase Plan [Abstract]
Percentage of earnings eligible employees may withhold under the employee stock purchase plan (in hundredths)	10.00%
Number of months each offering period last beginning on January 1 and July 1 each year (in months)	6
Percentage of the lower of fair market value of unit on the commencement date or fair market value of unit on the last trading day of the offering period (in hundredths)	85.00%
Number of shares sold through the plan (in shares)	25,300,000
Employee stock purchase plan [Member] | Offering period July 1 through December 31 [Member]
Fair value assumptions and methodology [Abstract]
Expected term (in years)	0.5	0.5	0.5
Expected volatility (in hundredths)	34.00%	43.00%	80.00%
Expected dividend yield (in hundredths)	0.70%	1.44%	1.74%
Risk-free interest rate (in hundredths)	0.10%	0.21%	0.33%
Weighted average grant-date fair value per share (in dollars per share)	$ 12.57	$ 6.72	$ 7.66
Employee stock purchase plan [Member] | Offering period January 1 through June 30 [Member]
Fair value assumptions and methodology [Abstract]
Expected term (in years)	0.5	0.5	0.5
Expected volatility (in hundredths)	43.00%	48.00%	71.00%
Expected dividend yield (in hundredths)	0.88%	1.15%	1.85%
Risk-free interest rate (in hundredths)	0.20%	0.19%	0.27%
Weighted average grant-date fair value per share (in dollars per share)	$ 10.99	$ 8.81	$ 6.69