Share-Based Compensation Plans (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Multiplier for grant award	2.33
Common Stock, Dividends, Per Share, Declared	$ 0.23	$ 0.22	$ 0.21
Weighted-average grant-date fair value per share	$ 26.36
Stock Options [Member]
Vesting period, years	in thirds over the three-year period
Contractual term, years	10
Weighted-average grant-date fair value per share	$ 6.51	$ 7.91	$ 3.18
Unrecognized compensation cost	$ 6.8
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1.2
Restricted Stock Units [Member]
Vesting period, years	after three years
Fair value vested during period	20.9
Restricted Stock Units and Performance Restricted Stock Units [Member]
Unrecognized compensation cost	$ 33.4
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	2.0
Performance Restricted Stock Units [Member]
Vesting period, years	three years only upon the satisfaction of certain performance conditions
2010 Plan [Member]
Maximum award, number of shares	32,000,000