Accumulated Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accumulated other comprehensive income (loss), net of income taxes [Line Items]
Balance, beginning of period	$ (4.4)	$ (6.8)	$ (20.3)
Changes during period	(8.9)	2.4	13.5
Balance, end of period	(13.3)	(4.4)	(6.8)
Unconsolidated Affiliates [Member]
Accumulated other comprehensive income (loss), net of income taxes [Line Items]
Balance, beginning of period	(6.6)	(7.1)	(29.0)
Changes during period	(9.3)	0.5	21.9
Balance, end of period	(15.9)	(6.6)	(7.1)
Pension and Other Benefit Costs [Member]
Accumulated other comprehensive income (loss), net of income taxes [Line Items]
Balance, beginning of period	(4.9)	(4.4)	(5.3)
Changes during period	(1.7)	(0.5)	0.9
Balance, end of period	(6.6)	(4.9)	(4.4)
Cash Flow Hedges [Member]
Accumulated other comprehensive income (loss), net of income taxes [Line Items]
Balance, beginning of period	4.0	0.1	0.1
Changes during period	(3.9)	3.9	0
Balance, end of period	0.1	4.0	0.1
Deferred Income Taxes [Member]
Accumulated other comprehensive income (loss), net of income taxes [Line Items]
Balance, beginning of period	3.1	4.6	13.9
Changes during period	6.0	(1.5)	(9.3)
Balance, end of period	$ 9.1	$ 3.1	$ 4.6