Income Taxes - Deferred Tax Assets (Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Deferred Tax Assets (Liabilities), Net [Abstract]
Deferred income taxes — current assets	$ 94.7		$ 58.5
Deferred income taxes — current liabilities	(1.4)		(6.5)
Other non-current assets	244.1	[1]	313.9	[1]
Other non-current liabilities	(89.4)	[1]	(120.2)	[1]
Net deferred tax asset	$ 248.0		$ 245.7

[1] urrent and non-current assets and liabilities have been netted within their respective taxing jurisdictions.