Share-Based Compensation, Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Share-based expense (net of estimated forfeitures) [Abstract]
Total share-based expense	$ 1.7	$ 2.0
Total recognized tax benefit	(0.5)	(0.6)
Share-based expense (net of tax)	1.2	1.4
Stock Options [Member]
Share-based expense (net of estimated forfeitures) [Abstract]
Total share-based expense	0.5	0.5
Non-Vested Stock & Restricted Stock Units [Member]
Share-based expense (net of estimated forfeitures) [Abstract]
Total share-based expense	$ 1.2	$ 1.5