Collaboration Agreements (Details) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Abbott Laboratories TRU016 [Member]	Jun. 30, 2012 Abbott Laboratories TRU016 [Member]	Jun. 30, 2012 Pfizer CD20 [Member]	Jun. 30, 2012 Pfizer CD20 [Member]	Dec. 31, 2011 Pfizer CD20 [Member]
Collaborative arrangements [Line Items]
Contracts and grants	$ 17,218,000	$ 16,662,000	$ 33,172,000	$ 29,598,000	$ 1,400,000	$ 2,700,000	$ 512,000	$ 877,000	$ 2,500,000