Financial Instruments (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Financial Instruments (Textual) [Abstract]
Federal Deposit Insurance Corporation guaranteed senior notes issued under the Temporary Liquidity Guarantee Program	$ 89.1		$ 89.1		$ 214.0
Original maturities of commercial paper and short-term debt securities			less than 90 days
Average maturity of marketable securities, months			13 months		14 months
Impairments recognized in relation to our publicly-held strategic investments			0
Impairment charges	$ 3.5	$ 0.8	$ 4.8	$ 7.6