Stock-based Compensation (Details 5) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Schedule of information on stock units
Undistributed, Beginning Balance	0.9
Undistributed, Weighted-Average Grant Date Fair Value per Share, Beginning Balance	$ 33.40
Granted	0.1
Granted, Weighted-Average Grant Date Fair Value per Share	$ 48.64
Distributed	(0.1)
Distributed, Weighted-Average Grant Date Fair Value per Share	$ 25.73
Forfeited	(0.1)
Forfeited, Weighted-Average Grant Date Fair Value per Share	$ 35.96
Undistributed, Ending Balance	0.7	[1]
Undistributed, Weighted-Average Grant Date Fair Value per Share, Ending Balance	$ 39.06	[1]
Restricted Stock [Member]
Schedule of information on stock units
Undistributed, Beginning Balance	0.6
Undistributed, Weighted-Average Grant Date Fair Value per Share, Beginning Balance	$ 36.51
Granted	0.2
Granted, Weighted-Average Grant Date Fair Value per Share	$ 48.45		$ 32.34	$ 44.80
Distributed	(0.2)
Distributed, Weighted-Average Grant Date Fair Value per Share	$ 35.16
Forfeited	(0.1)
Forfeited, Weighted-Average Grant Date Fair Value per Share	$ 36.55
Undistributed, Ending Balance	0.5		0.6
Undistributed, Weighted-Average Grant Date Fair Value per Share, Ending Balance	$ 40.50		$ 36.51

[1] Undistributed performance share units include approximately 0.5 million units with a weighted-average grant date fair value of $40.31 per share that had not yet vested and 0.2 million units that have vested but were not yet distributed.