Income Taxes Uncertain tax positions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 12	$ 12
Unrecognized Tax Benefits	49.9	23.5	11.3	13.0
Tax positions taken in current year	0.1	0	0
Tax positions taken in prior years	33.9	12.9	0.7
Tax positions taken in current year	0	(0.3)	(0.7)
Tax positions taken in prior years	(7.4)	(0.2)	0
Settlements during the year	(0.2)	(0.2)	(1.7)
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	2.0	1.2
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$ 5.5	$ 3.7