Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 12,052	$ 21,679
Marketable securities	35,224	41,868
Interest receivable	273	190
Accounts receivable	4,918	4,129
Other current assets	285	203
Prepaid expenses	969	296
Total current assets	53,721	68,365
Marketable securities, non-current	18,849	12,584
Property and equipment, net	1,587	1,543
Other assets	39	41
Total assets	74,196	82,533
Current liabilities:
Accounts payable and accrued liabilities	3,294	4,013
Accrued compensation and employee benefits	1,443	2,473
Deferred revenues	2,318	2,304
Total current liabilities	7,055	8,790
Deferred revenues, non-current	7,763	8,847
Total liabilities	14,818	17,637
Commitments and contingencies
Stockholders' equity:
Common stock, $0.01 par value; 80,000,000 shares authorized, 53,974,452 and 53,058,525 shares issued and outstanding at June 30, 2013 and December 31, 2012, respectively	540	531
Additional paid-in capital	346,683	339,848
Accumulated deficit	(287,844)	(275,509)
Accumulated other comprehensive income (loss)	(1)	26
Total stockholders' equity	59,378	64,896
Total liabilities and stockholders' equity	$ 74,196	$ 82,533