Investments (Realized Gains Losses Available-For-Sale Securities) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Schedule of Available-for-sale Securities [Line Items]
Proceeds from Sales	$ 60.2	$ 64.7	$ 18.8
Current Available-For-Sale Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from Sales	59.3	64.5	47.5
Gross Realized Gains	8.8	9.9	4.5
Gross Realized Losses	(1.2)	(1.3)	1.6
Non-current available-for-sale investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from Sales	0.9	0.2	2.2
Gross Realized Gains	0.6	0	1.4
Gross Realized Losses	$ 0	$ 0	$ 0