Balance Sheets and Statements of Operations Details (Property and Equipment, net) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Property, Plant and Equipment, Net, by Type [Abstract]
Property and Equipment, Gross	$ 37,907		$ 50,822
Less: accumulated depreciation and amortization	(29,461)		(34,172)
Property and equipment, net	8,446		16,650
Laboratory equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and Equipment, Gross	23,949		33,776
Leasehold improvements [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and Equipment, Gross	9,493		4,388
Computer equipment and software [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and Equipment, Gross	3,196		11,099
Office equipment and furniture [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and Equipment, Gross	1,228		1,531
Construction in progress [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and Equipment, Gross	$ 41	[1]	$ 28	[1]

[1] Construction in progress includes equipment received but not yet placed into service pending installation.