License and Collaboration Agreements - License, Collaboration and Other Revenue (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	$ 80,872	$ 30,127	$ 36,289
AstraZeneca AB [Member] | Naloxegol (NKTR-118) and Naloxegol Fixed-dose Combination Program (NKTR-119) [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	25,016	59	2,496
Roche [Member] | PEGASYS and MIRCERA [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	18,382	7,146	5,131
Bayer Healthcare LLC [Member] | BAY41-6551 (Amikacin Inhale) [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	15,293	2,971	2,992
Affymax, Inc. [Member] | OMONTYS [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	7,149	2,829	3,838
Amgen, Inc. [Member] | Neulasta [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	5,035	5,000	5,000
Baxter Healthcare [Member] | BAX 855 (Hemophilia) [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	1,702	6,238	5,646
Other [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	$ 8,295	$ 5,884	$ 11,186