Balance Sheets Details (Property and Equipment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 37,743	$ 37,743		$ 37,866
Less: accumulated depreciation and amortization	(31,064)	(31,064)		(29,461)
Property and equipment, net, excluding construction in progress	6,679	6,679		8,405
Property and equipment	6,694	6,694		8,446
Less: Impairment of laboratory equipment	(1,841)	(1,841)	0
Property and equipment, net	4,853	4,853		8,446
Laboratory equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	23,774	23,774		23,949
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	9,493	9,493		9,493
Computer equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,249	3,249		3,196
Office equipment and furniture [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,227	1,227		1,228
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 15	$ 15		$ 41