Non- Marketable Investments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended					3 Months Ended	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Dec. 31, 2008	Dec. 31, 2007	Sep. 30, 2012 Technology Related Private Equity Funds [Member]	Dec. 31, 2011 Technology Related Private Equity Funds [Member]	Sep. 30, 2012 Non Marketable Investments [Member]	Sep. 30, 2012 Non Marketable Investments [Member]	Sep. 30, 2011 Non Marketable Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Carrying Value of the Company's non-marketable investments					$ 7.8	$ 7.9
Gain from non- marketable investments							0.1	0.3	0.6
Non- Marketable Investments (Textual) [Abstract]
Ownership interest of company	5.00%
Book value of investment	1.4	1.5
Income from equity method investment understated amount			0.2	0.4
Income from equity method investment understated amount		1.2
Reduction in income from equity method investment	$ 0.6