License and Collaboration Agreements (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
License, collaboration, and other revenue
License, collaboration and other	$ 6,323	$ 31,409	$ 12,829	$ 61,062
BAY41-6651 (Amikacin Inhale) [Member] | Bayer Healthcare LLC [Member]
License, collaboration, and other revenue
License, collaboration and other	750	818	1,500	1,705
NKTR-118 and NKTR-119 [Member] | AstraZeneca AB [Member]
License, collaboration, and other revenue
License, collaboration and other	845	27,579	1,086	53,306
Pegasys [Member] | F Hoffmann La Roche [Member]
License, collaboration, and other revenue
License, collaboration and other	1,283	1,283	2,566	2,566
Neulasta [Member] | Amgen Inc [Member]
License, collaboration, and other revenue
License, collaboration and other	1,250	0	2,500	0
Other Partner [Member]
License, collaboration, and other revenue
License, collaboration and other	$ 2,195	$ 1,729	$ 5,177	$ 3,485