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The fair value of available-for-sale securities that serve as collateral for borrowings.

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Investments (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended				12 Months Ended
	Sep. 30, 2011	Sep. 30, 2011	Sep. 30, 2011 Traville Lease [Member]	Sep. 30, 2011 LSM Lease [Member]	Sep. 30, 2011 MEDCO Lease [Member]	Dec. 31, 2010 Other Assets [Member]
Interest rate of convertible subordinated notes	2.25%	2.25%
Convertible subordinated notes due date		August 15, 2012
Convertible subordinated notes due within next 12 months	$ 206,736	$ 206,736
Cash security deposit to be maintained with the landlord with respect to the headquarters lease			19,750	19,750
Margin value of the collateral, minimum			19,750
Pledge to landlord in marketable securities, minimum				$ 20,000	$ 34,300
Number of leases with the Maryland Economic Development Corporation		2
Letter of credit, expiration date		December 2011
Number of available-for-sale securities owned	340	340
Number of securities with unrealized losses	92	92
Percentage of cost investments in privately-held Companies						20.00%