Property and Equipment, Net (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property and equipment, net
Property and equipment, gross	$ 25,266,000	$ 22,336,000
Less: Accumulated depreciation and amortization	(18,969,000)	(16,130,000)
Property and equipment, net	6,297,000	6,206,000
Depreciation	3,510,000	5,006,000	4,059,000
Gross amount of fully depreciated fixed assets disposed			26,000
Gross amount of fully depreciated fixed assets disposed	671,000
Recognized impairment charges	0	0	0
Lab equipment
Property and equipment, net
Property and equipment, gross	12,616,000	11,757,000
IT equipment
Property and equipment, net
Property and equipment, gross	2,346,000	2,204,000
Leasehold improvements
Property and equipment, net
Property and equipment, gross	8,200,000	7,698,000
Furniture and fixtures
Property and equipment, net
Property and equipment, gross	330,000	329,000
Construction in process
Property and equipment, net
Property and equipment, gross	1,774,000	348,000
Property and equipment under capital leases
Property and equipment, net
Property and equipment, net	0	4,114,000
Depreciation	$ 0	$ 26,000	$ 409,000