Share-Based Compensation, Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Share-based expense (net of estimated forfeitures) [Abstract]
Total share-based expense	$ 2.1	$ 1.1	$ 3.4	$ 2.4
Total recognized tax benefit	(0.7)	(0.2)	(1.1)	(0.6)
Share-based expense (net of tax)	1.4	0.9	2.3	1.8
Stock Options [Member]
Share-based expense (net of estimated forfeitures) [Abstract]
Total share-based expense	1.1	0.3	1.4	0.6
Non-Vested Stock & Restricted Stock Units [Member]
Share-based expense (net of estimated forfeitures) [Abstract]
Total share-based expense	$ 1.0	$ 0.8	$ 2.0	$ 1.8