Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 22,159	$ 26,487
Accounts receivable, net of allowances of $421 at March 31, 2015 and $428 at December 31, 2014	3,215	3,870
Inventories	992	1,395
Prepaid expenses and other current assets	1,266	1,255
Total current assets	27,632	33,007
Restricted cash	711	711
Marketable securities	712	688
Property and equipment, net	3,499	3,995
Intangible assets, net	5,342	6,186
Goodwill	3,241	3,241
Other non-current assets	284	294
Total assets	41,421	48,122
Current liabilities:
Accounts payable	1,952	4,673
Accrued compensation	3,600	2,946
Other accrued liabilities	2,065	2,619
Deferred revenue	4,253	3,497
Total current liabilities	11,870	13,735
Deferred revenue, net of current portion	3,780	3,813
Other long-term liabilities	4,154	4,263
Commitments and contingencies (note 11)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 5,000 shares authorized, none issued and outstanding	0	0
Common stock, $0.0001 par value; 100,000 shares authorized at March 31, 2015 and December 31, 2014; shares issued and outstanding of 39,868 at March 31, 2015 and 39,563 at December 31, 2014	4	4
Additional paid-in capital	303,231	302,379
Accumulated other comprehensive income loss	(126)	(142)
Accumulated deficit	(281,492)	(275,930)
Total stockholders’ equity	21,617	26,311
Total liabilities and stockholders’ equity	$ 41,421	$ 48,122