Collaboration And License Agreements (Summary Of Research And Development Expenses Incurred And Funding Provided To Agensys) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Collaboration And License Agreements [Abstract]
Research and development expense using contractual rates	$ 6,404	$ 4,654	$ 4,824
Co-development funding due to Agensys	6,844	360	764
Total	$ 13,248	$ 5,014	$ 5,588