Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 12,751	$ 18,873
Short-term investments	15,513	13,328
Accounts receivable, net of allowances for doubtful accounts and other adjustments of $490 (2013) and $482 (2012)	9,804	8,953
Income tax receivable	681	681
Inventories, net of reserves for excess and obsolete inventory of $330 (2013) and $352 (2012)	133	176
Prepaid expenses and other current assets	729	903
Deferred tax asset	89	89
Total current assets	39,700	43,003
Equipment and improvements, net	10,228	11,211
Other assets	184	181
Total assets	50,112	54,395
Current liabilities:
Accounts payable	1,788	1,978
Accrued liabilities	6,227	4,829
Deferred revenue	1,605	1,436
Total current liabilities	9,620	8,243
Non-current liabilities:
Deferred rent and other long-term liabilities	2,960	3,399
Deferred tax liability	91	91
Total non-current liabilities	3,051	3,490
Commitments and contingencies
Stockholders' equity:
Preferred stock, par value $0.001 per share; 5,000,000 shares authorized; none issued or outstanding
Common stock, par value $0.001 per share; 100,000,000 shares authorized; 37,262,069 and 35,873,418 shares issued and outstanding at March 31, 2013 and December 31, 2012, respectively	37	36
Additional paid-in capital	212,083	211,165
Accumulated comprehensive deficit	(174,679)	(168,539)
Total stockholders' equity	37,441	42,662
Total liabilities and stockholders' equity	$ 50,112	$ 54,395