Stock-Based Compensation Plans (Details 9) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Schedule of information on stock units
Undistributed, Beginning Balance	0.8
Granted	0.3
Forfeited	0
Undistributed, Ending Balance	0.9
Stock Appreciation Rights [Member]
Schedule of information on stock units
Undistributed, Beginning Balance	2.5	2.9	2.7
Nonvested, Weighted-Average Exercise Price per Share, Beginning Balance	$ 34.89	$ 31.06	$ 29.59
Granted	0.7	0.5	0.6
Granted, Weighted-Average Exercise Price per Share	$ 34.06	$ 46.78	$ 36.94
Exercised	(0.2)	(0.7)	(0.2)
Exercised, Weighted-Average Exercise Price per Share	$ 31.67	$ 27.20	$ 28.31
Forfeited	(0.1)	(0.2)	(0.2)
Forfeited, Weighted-Average Exercise Price per Share	$ 39.39	$ 31.97	$ 30.59
Undistributed, Ending Balance	2.9	2.5	2.9
Nonvested, Weighted-Average Exercise Price per Share, Ending Balance	$ 34.85	$ 34.89	$ 31.06
Exercisable at end of year, shares	1.8	1.5	1.6
Exercisable at end of year, Weighted-Average Exercise Price per Share	$ 33.05	$ 31.81	$ 29.58