CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 7,698	$ 14,572
Short-term investments	11,511	29,201
Inventory	4,074	3,204
Accounts receivable	997	839
Due from related parties	51	75
Unbilled receivables	187	372
Prepaid expenses and other current assets	713	692
Total current assets	25,231	48,955
Restricted cash	619	594
Property and equipment, net	793	1,358
Long-term investments		2,508
Other assets	95	95
Total assets	26,738	53,510
Current Liabilities:
Accounts payable	579	1,233
Accrued expenses	4,892	3,519
Current portion of deferred rent	55	165
Short-term deferred revenue	669	1,067
Total current liabilities	6,195	5,984
Deferred rent, net of current portion		55
Other long-term liabilities	145	131
Total liabilities	6,340	6,170
Commitments and contingencies (Note 9)
Stockholders' Equity:
Preferred stock ($0.01 par value per share); 5,000,000 shares authorized; no shares issued or outstanding
Common stock ($0.01 par value per share); 100,000,000 shares authorized at December 31, 2013 and 2012, 34,581,449 and 34,306,570 shares issued and outstanding at December 31, 2013 and 2012, respectively	346	343
Additional paid-in capital	292,661	289,050
Accumulated other comprehensive loss	(71)	(21)
Accumulated deficit	(272,538)	(242,032)
Total stockholders' equity	20,398	47,340
Total liabilities and stockholders' equity	$ 26,738	$ 53,510