Supplemental Data (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supplemental Disclosure of Cash Flow Information
Cash paid during the year for interest, net of interest expense capitalized	$ 13.1	$ 15.2	$ 18.9
Cash paid during the year for income taxes, net of refunds	6.7	4.7	0.5
Non-cash investing activities:
Liability for equipment acquired	2.2	2.4	2.9
Net cash provided by (used in) changes in working capital
Accounts receivable	(7.7)	(1.9)	(5.3)
Inventories	(26.8)	(0.1)	(0.3)
Income taxes (receivable) payable	(1.1)	(0.5)	2.9
Prepaid and other current assets		(0.1)	(0.7)
Accounts payable	5.0	0.5	2.6
Accrued expenses	9.7	(5.1)	(3.1)
Net cash provided by (used in) changes in operating working capital (Note 15)	$ (20.9)	$ (7.2)	$ (3.9)