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	$ 0.8	$ 0.7	$ 1.8	$ 1.3
Total recognized tax benefit	(0.3)	(0.3)	(0.7)	(0.5)
Share-based expense (net of tax)	0.5	0.4	1.1	0.8
Stock Options [Member]
Share-based expense (net of estimated forfeitures) [Abstract]
Total share-based expense	0.2	0.2	0.4	0.4
Non-Vested Stock & Restricted Stock Units [Member]
Share-based expense (net of estimated forfeitures) [Abstract]
Total share-based expense	$ 0.6	$ 0.5	$ 1.4	$ 0.9