License and Collaboration Agreements (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
License, collaboration, and other revenue
License, collaboration and other revenue	$ 6,614	$ 16,846	$ 6,323	$ 6,506	$ 32,615	$ 30,695	$ 31,409	$ 29,653	$ 36,289	$ 124,372	$ 36,643
Baxter Healthcare [Member] | Hemophilia [Member]
License, collaboration, and other revenue
License, collaboration and other revenue									5,646	1,701	2,055
F Hoffmann La Roche [Member] | PEGASYS [Member]
License, collaboration, and other revenue
License, collaboration and other revenue									5,131	5,131	214
Amgen Inc [Member] | Neulasta [Member]
License, collaboration, and other revenue
License, collaboration and other revenue									5,000	833
Bayer Healthcare L L C [Member] | BAY41-6551 (Amikacin Inhale) [Member]
License, collaboration, and other revenue
License, collaboration and other revenue									2,992	3,300	4,928
AstraZeneca AB [Member] | NKTR-118 and NKTR-119 [Member]
License, collaboration, and other revenue
License, collaboration and other revenue									2,496	107,854	25,073
Other [Member]
License, collaboration, and other revenue
License, collaboration and other revenue									$ 15,024	$ 5,553	$ 4,373