Share-Based Incentive Compensation (details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010	Dec. 31, 2009
Share-Based Incentive Compensation disclosure
Number of shares of the Company's common stock authorized for grant under the 2004 Incentive Plan	35,000,000
Compensation program for non-employee directors	Under the Director Compensation Program, non-employee directors' compensation consists of an annual retainer, a deferred stock award, committee chair fees and a lead director fee. Each non-employee director may choose to receive all or a portion of his or her annual retainer in the form of cash or deferred stock units which vest upon grant. The annual deferred stock awards vest in full one day prior to the date of the Company's annual meeting of shareholders occurring in the year following the year of the grant date, subject to continued service. Any of the deferred stock awards may accumulate, including reinvestment dividends, until distribution either in a lump sum six months after termination of service as a director or, if the director so elects, in annual installments beginning at least six months following termination of service as a director. The shares of deferred stock units issued under the Director Compensation Program are awarded under the 2004 Incentive Plan.
Discount applied to the fair value of reload options to reflect sales restrictions, as measured by the estimated cost of protecting against changes in market value	A discount, as measured by the estimated cost of protecting against changes in market value, 5% for one year sales restrictions and 10% for two year sales restrictions, has been applied to the fair value of reload options granted to reflect these sales restrictions.
Stock options outstanding, beginning of year, number (in shares)	22,476,981
Stock options exercised, number (in shares)	(6,845,142)
Stock options forfeited or expired, number (in shares)	(2,373,892)
Stock options outstanding, end of year, number (in shares)	16,212,961	22,476,981
Stock options outstanding, beginning of year, weighted average exercise price (per share)	$ 46.52
Stock options exercised, weighted average exercise price (per share)	$ 46.03
Stock options forfeited or expired, weighted average exercise price (per share)	$ 56.61
Stock options outstanding, end of year, weighted average exercise price (per share)	$ 47.33	$ 46.52
Stock options outstanding, weighted average contractual life remaining (in years)	5.4
Stock options outstanding, aggregate intrinsic value	$ 194
Stock options vested at end of year, number (in shares)	12,218,772
Stock options vested at end of year, weighted average exercise price (per share)	$ 46.71
Stock options vested at end of year, weighted average contractual life remaining (in years)	4.5
Stock options vested at end of year, aggregate intrinsic value	154
Stock options exercisable at end of year, number (in shares)	8,625,125
Stock options exercisable at end of year, weighted average exercise price (per share)	$ 45.22
Stock options exercisable at end of year, weighted average contractual life remaining (in years)	3.4
Stock options exercisable at end of year, aggregate intrinsic value	121
Fair value of shares that vested during the year	121	113	78
Description of share-based compensation cost recognition	The amount of compensation cost for awards subject to a service condition is based on the number of shares expected to be issued and is recognized over the time period for which service is to be provided (requisite service period). Awards granted to retiree-eligible employees or to employees who become retiree-eligible before an award's vesting date are considered to have met the requisite service condition. The compensation cost for awards subject to a performance condition is based upon the probable outcome of the performance condition, which on the grant date reflects an estimate of attaining 100% of the performance shares granted. The compensation cost reflects an estimated annual forfeiture rate from 3.5% to 4% over the requisite service period of the awards. That estimate is revised if subsequent information indicates that the actual number of instruments expected to vest is likely to differ from previous estimates. Compensation costs for awards are recognized on a straight-line basis over the requisite service period. For awards that have a graded vesting schedule, the compensation cost is recognized on a straight-line basis over the requisite service period for each separate vesting portion of the award as if the award was, in substance, multiple awards.
Estimated annual forfeiture rate reflected in share-based compensation cost, minimum (percent)	3.50%
Estimated annual forfeiture rate reflected in share-based compensation cost, maximum (percent)	4.00%
Total compensation cost recognized in earnings for all share-based incentive compensation awards	121	128	127
Compensation cost adjustments for the updated estimate of performance shares due to attaining certain performance levels	4	10	11
Tax benefits recognized in the consolidated statement of income related to compensation costs	42	44	44
Total unrecognized compensation cost related to all nonvested share-based incentive compensation awards	114
Weighted-average period of recognition for unrecognized compensation cost (in years)	1.7
Cash received from the exercise of employee stock options under share-based compensation plans	314	408	180
Tax benefit realized for tax deductions from employee stock options	$ 30	$ 28