Stock-Based Compensation Plans (Details 6) (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
Undistributed, Weighted-Average Grant Date Fair Value per Share, Beginning Balance	$ 33.90
Granted	0.3
Granted, Weighted-Average Exercise Price per Share	$ 31.78
Vested	0
Vested, Weighted-Average Grant Date Fair Value per Share	$ 0.00
Forfeited	0
Forfeited, Weighted-Average Grant Date Fair Value per Share	$ 35.45
Undistributed, Ending Balance	0.9
Undistributed, Weighted-Average Grant Date Fair Value per Share, Ending Balance	$ 33.40
Restricted Stock Units [Member]
Schedule of information on stock units
Undistributed, Beginning Balance	0.6
Undistributed, Weighted-Average Grant Date Fair Value per Share, Beginning Balance	$ 34.44
Granted	0.3
Granted, Weighted-Average Exercise Price per Share	$ 32.34	$ 44.80	$ 35.09
Vested	(0.3)
Vested, Weighted-Average Grant Date Fair Value per Share	$ 26.91
Forfeited	0
Forfeited, Weighted-Average Grant Date Fair Value per Share	$ 35.80
Undistributed, Ending Balance	0.6	0.6
Undistributed, Weighted-Average Grant Date Fair Value per Share, Ending Balance	$ 36.51	$ 34.44