Supplemental Cash Flows Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supplemental Cash Flows Information [Abstract]
Cash paid for income taxes	$ 20.4	$ 13.5	$ 35.7
Capital Expenditures Incurred but Not yet Paid	0.6	0.8	0.3
Tax Benefit from Stock Options Exercised	3.3	15.8	2.7
Business Acquisition, Contingent Consideration, Potential Cash Payment	2.5	1.0	2.2
Interest Paid	$ 0.4	$ 0.1	$ 0.1