Stock Based Compensation Plans, Summary information of stock options outstanding (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options outstanding, ending balance (in shares)	415,020,000
Options outstanding, weighted-average remaining contractual life (in years)	6.8
Options outstanding, weighted-average exercise price (in dollars per share)	109.71
Number of options exercisable, ending balance (in shares)	219,820,000
Options exercisable, weighted-average exercise price (in dollars per share)	92.31
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)	1,540	14,415	18,954
Unrecognized compensation cost, weighted average recognition period (in years)		6
48.68-73.38 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	48.68
Exercise price range, upper range limit (in dollars per share)	73.38
Number of options outstanding, ending balance (in shares)	50,577,000
Options outstanding, weighted-average remaining contractual life (in years)	2.8
Options outstanding, weighted-average exercise price (in dollars per share)	61.78
Number of options exercisable, ending balance (in shares)	50,577,000
Options exercisable, weighted-average exercise price (in dollars per share)	61.78
79.05-125.84 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	79.05
Exercise price range, upper range limit (in dollars per share)	125.84
Number of options outstanding, ending balance (in shares)	167,693,000
Options outstanding, weighted-average remaining contractual life (in years)	5.0
Options outstanding, weighted-average exercise price (in dollars per share)	97.70
Number of options exercisable, ending balance (in shares)	148,193,000
Options exercisable, weighted-average exercise price (in dollars per share)	97.15
126.73-132.62 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	126.73
Exercise price range, upper range limit (in dollars per share)	132.62
Number of options outstanding, ending balance (in shares)	196,750,000
Options outstanding, weighted-average remaining contractual life (in years)	9.8
Options outstanding, weighted-average exercise price (in dollars per share)	132.27
Number of options exercisable, ending balance (in shares)	21,050,000
Options exercisable, weighted-average exercise price (in dollars per share)	131.66