Incentive Compensation Expense (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Stock-based Payment Award
Stock-based compensation expense	$ 50.4		$ 62.4		$ 66.8
Tax benefit	19.7		22.1		22.1
Stock options
Stock-based Payment Award
Stock-based compensation expense	5.4		6.7		7.4
Stock-settled awards
Stock-based Payment Award
Stock-based compensation expense	14.9		21.9		32.7
Cash-settled awards
Stock-based Payment Award
Stock-based compensation expense	3.9		5.7		10.9
Performance-based awards
Stock-based Payment Award
Stock-based compensation expense	24.5		23.3		11.0
Employee stock purchase plan
Stock-based Payment Award
Stock-based compensation expense	0.6		0.7		0.5
Other
Stock-based Payment Award
Stock-based compensation expense	1.1	[1]	4.1	[1]	4.3	[1]
Time based cash awards
Stock-based Payment Award
Incentive compensation expense, Non share-based	10.9		16.6		12.8
Performance based cash awards
Stock-based Payment Award
Incentive compensation expense, Non share-based	$ 18.9		$ 22.0		$ 11.4

[1] Represents charges recorded for severance expense related to stock-based compensation awards.