Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 17,306	$ 17,715
Marketable securities	8,578
Restricted cash		5,051
Receivables	129
Inventory	3,447
Prepaid expenses and other current assets	1,453	852
Total current assets	30,913	23,618
Property and equipment, net	14,991	16,531
Other assets	1,168	402
Total assets	47,072	40,551
Current liabilities:
Accounts payable	3,789	2,147
Accrued clinical trial liabilities	178	96
Other accrued liabilities	4,736	3,599
Current portion of contingent consideration liability	2,500	3,500
Current portion of financing obligations	780	6,461
Current portion of deferred revenues	2,915	2,915
Total current liabilities	14,898	18,718
Deferred rent	6,405	8,059
Noncurrent portion of contingent consideration liability	36,700	6,100
Noncurrent portion of deferred revenues	2,185	5,101
Noncurrent portion of financing obligations	10,744
Other liabilities	115
Commitments (See Note 6)
Stockholders' equity (deficit):
Preferred stock, $0.0001 par value, 5,000,000 shares authorized at December 31, 2013 and 2012; no shares issued and outstanding at December 31, 2013 or 2012
Common stock, $0.0001 par value; 200,000,000 shares authorized at December 31, 2013 and 2012, respectively; 17,279,804 and 15,767,525 shares issued and outstanding at December 31, 2013 and 2012, respectively	2	2
Additional paid-in capital	350,250	337,184
Accumulated other comprehensive income	1
Accumulated deficit	(374,228)	(334,613)
Total stockholders' (deficit) equity	(23,975)	2,573
Total liabilities and stockholders' equity (deficit)	$ 47,072	$ 40,551