Stock-Based Employee Compensation Plans (Details 2) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Y
Additional information with respect to stock options [Abstract]
Weighted Average Remaining Contractual Term (in years) on Number of Shares Outstanding, December 31, 2011	1.9
Aggregate Intrinsic Value on Number of Shares Outstanding, December 31, 2011	$ 54
Number of Shares Outstanding, January 1,2011	3,158,696
Number of Shares Outstanding, December 31, 2011	1,724,440
Number of Shares, Granted	38,753
Weighted Average Exercise Price on Number of Shares, Granted	$ 60.56
Number of Shares, Exercised	(1,425,571)
Weighted Average Exercise Price on Number of Shares, Exercised	$ 37.99
Number of Shares, Forfeited	(47,438)
Weighted Average Exercise Price on Number of Shares, Forfeited	$ 39.31
Weighted Average Exercise Price on Number of Shares Outstanding, December 31, 2011	$ 37.71
Weighted Average Exercise Price on Number of Shares Outstanding, January 1, 2011	$ 37.58
Number of Shares Exercisable, December 31, 2011	1,594,577
Weighted Average Exercise Price on Number of Shares Exercisable, December 31, 2011	$ 36.66
Weighted Average Remaining Contractual Term (in years) on Number of Shares Exercisable, December 31, 2011	1.4
Aggregate Intrinsic Value on Number of Shares Exercisable, December 31, 2011	$ 52