Income Taxes (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Income Tax Contingency [Line Items]
Unrecognized tax benefits	$ 114.0
Interest expense, uncertain tax positions	0.3	0
Accrued interest, uncertain tax positions	0.3		0
Unrecognized tax benefits that would impact effective tax rate	$ 79.1
Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Earliest year subject to examination	2000