Collaboration Agreements (Tables)

3 Months Ended

Mar. 31, 2012

Collaboration Agreements [Abstract]

Deferred Revenue

	March 31, 2012		December 31, 2011
Current portion:
Deferred revenue from Astellas	$	23,747	$	23,747
Deferred revenue from Pfizer		41,142		36,015
Total	$	64,889	$	59,762
Long-term portion:
Deferred revenue from Astellas	$	41,557	$	47,494
Deferred revenue from Pfizer		—		36,015
Total	$	41,557	$	83,509

Schedule Of Collaboration Revenue

	Three months ended March 31,
	2012		2011
Collaboration revenue from Astellas	$	5,937	$	5,705
Collaboration revenue from Pfizer		30,888		9,004
Total	$	36,825	$	14,709

Development And Commercialization Cost-Sharing Payments Receivable

	Three months ended March 31,
	2012		2011
Development cost-sharing payments from Astellas	$	14,115	$	9,887
Development cost-sharing payments from Pfizer		1,327		4,915
Total	$	15,442	$	14,802

	Three months ended March 31,
	2012			2011
Commercialization cost-sharing payments to Astellas	$	(816	)	$	(68	)
Commercialization cost-sharing payments from Pfizer		4			13
Total	$	(812	)	$	(55	)