Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Mar. 31, 2011	Dec. 31, 2010
Income Taxes (Textual) [Abstract]
Income tax provision	$ 19.7	$ 16.1	$ 53.5	$ 41.3
Effective income tax rate	26.60%	27.40%	28.70%	29.00%
Income tax assessment including interest under Canada Revenue Agency audit					8
Expected recovery of U.S. federal and state income taxes					7
Tax reserve associated with outstanding tax issue released			1.5
Net deferred tax assets (liabilities)						12.4
Net deferred tax liability	$ 5.6		$ 5.6