Supplemental Information (Details 1) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of Components of Interest Expense
Interest expense, net of capitalized interest	$ 18.9	$ 18.7	$ 13.7
Investment income	1.8	1.9	0.9
INTEREST EXPENSE, net	$ 17.1	$ 16.8	$ 12.8