Share-Based Compensation Plans (Schedule of Summary of Stock Options) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Outstanding, beginning balance, in shares	29,655
Granted, in shares	1,041
Exercised, in shares	(941)
Forfeited, in shares	(373)
Expired, in shares	(1,021)
Outstanding, ending balance, in shares	28,361
Exercisable, ending balance, in shares	22,732
Outstanding, beginning balance, weighted-average exercise price	$ 31.07
Granted, weighted-average exercise price	$ 27.31
Exercised, weighted-average exercise price	$ 17.71
Forfeited, weighted-average exercise price	$ 22.56
Expired, weighted-average exercise price	$ 36.31
Outstanding, ending balance, weighted-average exercise price	$ 31.30
Exercisable, ending balance, weighted-average exercise price	$ 32.60
Outstanding, ending balance, weighted-average contractual term, years	4.8
Outstanding, exercisable, weighted-average contractual term, years	4.1
Outstanding, ending balance, aggregate intrinsic value	$ 10.0
Exercisable, ending balance, aggregate intrinsic value	$ 6.2