License and Collaboration Agreements - License, Collaboration and Other Revenue (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	$ 60,382	$ 165,604	$ 153,289
AstraZeneca AB [Member] | MOVANTIK and MOVANTIK fixed-dose combination program [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	33,000	130,000	105,001
Roche [Member] | PEGASYS and MIRCERA [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	7,685	12,816	12,845
Amgen, Inc. [Member] | Neulasta [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	5,000	5,000	5,000
Daiichi Sankyo Europe GmbH [Member] | ONZEALDTM (NKTR-102) [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	3,690	0	0
Bayer Healthcare LLC [Member] | BAY41-6551 (Amikacin Inhale) [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	1,429	1,919	4,717
Baxalta Incorporated [Member] | ADYNOVATE [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	650	10,694	10,258
Other [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	$ 8,928	$ 5,175	$ 15,468