Balance Sheets Details (Property and Equipment, net) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 35,436	$ 35,324
Less: accumulated depreciation and amortization	(32,680)	(32,215)
Property and equipment, net	2,756	3,109
Laboratory equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	20,534	20,503
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	10,395	10,369
Computer equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,271	3,271
Office furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,179	1,178
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 57	$ 3