Accounts Receivable (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 61.3	$ 52.9
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	44.0	34.6
Other receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	17.3	18.3
Canadian Harmonized Sales Tax
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 13.8	$ 12.9