Stock-Based Compensation (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Shares reserved for awards to employees and outside directors	75,000,000
Maximum option term, years	10
Shares to be issued under various stock-based awards other than options and stock appreciation rights	18,750,000
Tax benefit associated with stock-based compensation	$ 20	$ 26	$ 16
Exercisable options	4,256,000	12	17
Weighted average exercise price of exercisable options	$ 15	$ 17	$ 18
Vesting period minimum, years	three
Vesting period maximum, years	five
Phantom Awards [Member]
Unrecognized compensation cost	19
Unrecognized compensation cost, period of recognition, years	2.6
Total grant date fair value of shares vested	19	29	23
Performance Awards [Member]
Unrecognized compensation cost	17
Unrecognized compensation cost, period of recognition, years	1.5
Total grant date fair value of shares vested	33	15	20
Other Stock Awards [Member]
Total grant date fair value of shares vested	$ 4	$ 1	$ 1