Share-Based Compensation (Expense Related to Non-vested Stock Awards) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Total pre-tax share-based compensation expense	$ 11.7		$ 9.3		$ 10.9
Excess tax benefit on share-based compensation	1.0	[1]	(0.1)	[1]	0.7	[1]
Non-Qualified Stock Option Expense [Member]
Total pre-tax share-based compensation expense	4.8		4.2		5.0
Non-Vested Stock Awards Expense [Member]
Total pre-tax share-based compensation expense	2.8		4.2		4.1
Outstanding Stock Awards [Member]
Total pre-tax share-based compensation expense	3.1		0.9		1.8
Performance-Based Non-Vested Stock Awards Expense [Member]
Total pre-tax share-based compensation expense	$ 1.0		$ 0		$ 0

[1] Cash inflows (outflows) recognized as financing and operating activities in the Company’s consolidated statement of cash flows