Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 17,097	$ 18,005
Short-term marketable securities	78,980	81,060
Accounts receivable (net of allowance for doubtful accounts; 2013 - $1,393, 2012 - $1,133)	27,045	22,253
Prepaid expenses and other current assets	9,517	8,891
Total current assets	132,639	130,209
Property and equipment, net	14,834	14,104
Other assets	9,527	9,421
Total assets	157,000	153,734
Current liabilities:
Accounts payable	3,983	4,881
Accrued compensation	9,378	11,210
Accrued license fees	2,076	2,292
Accrued expenses and other current liabilities	8,773	6,340
Deferred revenues	53	374
Other current liabilities	243	243
Total current liabilities	24,506	25,340
Other liabilities	1,915	2,068
Commitments and contingencies
Stockholders' equity:
Common stock	3	3
Additional paid-in capital	319,048	313,915
Accumulated other comprehensive income	33	15
Accumulated deficit	(158,395)	(157,512)
Treasury stock, at cost	(30,110)	(30,095)
Total stockholders' equity	130,579	126,326
Total liabilities and stockholders' equity	$ 157,000	$ 153,734