Restricted Cash (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011 M	Dec. 31, 2010
Restricted Cash
Restricted cash designated as collateral for a letter of credit related to an office and laboratory space lease		$ 1,778
Initial lease term during which cash will remain restricted (in months)	80
Extended lease term during which cash will remain restricted (in months)	48
Collateral for a security bond posted in the litigation	$ 17,500

- Definition

The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. For a classified balance sheet represents the current portion only (the noncurrent portion has a separate concept); there is a separate and distinct element for unclassified presentations.

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