Collaboration Agreements (Development And Commercialization Cost-Sharing Payments Receivable) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Development Milestone Payments [Member]
Collaboration Agreements [Line Items]
Development cost-sharing payments	$ 56,650	$ 63,264	$ 23,219
Commercial Milestone Payments [Member]
Collaboration Agreements [Line Items]
Commercialization cost sharing payments	(440)	(564)	(646)
Astellas [Member] | Development Milestone Payments [Member]
Collaboration Agreements [Line Items]
Development cost-sharing payments	44,285	34,125	2,784
Astellas [Member] | Commercial Milestone Payments [Member]
Collaboration Agreements [Line Items]
Commercialization cost sharing payments	(472)	520	74
Pfizer [Member] | Development Milestone Payments [Member]
Collaboration Agreements [Line Items]
Development cost-sharing payments	12,365	29,139	20,435
Pfizer [Member] | Commercial Milestone Payments [Member]
Collaboration Agreements [Line Items]
Commercialization cost sharing payments	$ 32	$ (1,084)	$ (720)