Accounts Receivable (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 56.5	$ 52.9
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	54.2	34.6
Other receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	7.7	18.3
Canadian Harmonized Sales Tax
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 4.4	$ 12.9