Fair Value Disclosures (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Fair Value Disclosure [Line Items]
Available-for-sale securities, maturities of less than a year	$ 2.8		$ 2.8
Impairment charge			0	1.2
Government [Member]
Fair Value Disclosure [Line Items]
Net realized gain on available for sale debt securities	0	0.1	0.3	0.4
Corporate/Other Bonds [Member]
Fair Value Disclosure [Line Items]
Net realized gain on available for sale debt securities	$ 0.1	$ 0.1	$ 0.1	$ 1.0