Balance Sheets Details - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 21,778	$ 21,778
Accumulated Amortization	(21,778)	(18,966)
Net Carrying Amount	0	2,812
Developed and core technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,534	1,534
Accumulated Amortization	(1,534)	(1,534)
Net Carrying Amount	$ 0	0
Weighted- Average Amortization Period	5 years
Maxygen intellectual property
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 20,244	20,244
Accumulated Amortization	(20,244)	(17,432)
Net Carrying Amount	$ 0	$ 2,812
Weighted- Average Amortization Period	6 years