CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Current assets:
Cash and cash equivalents	$ 56,099	$ 70,105	$ 88,654
Accounts receivable	2,403	1,516
Other current assets	960	919
Total current assets	59,462	72,540
Auction rate securities	3,240	3,332
Fixed assets, at cost, net of accumulated depreciation and amortization	4,004	4,038
Other assets	200	200
Total assets	66,906	80,110
Current liabilities:
Accounts payable and accrued expenses	4,099	6,331
Deferred revenue - current	204	204
Other current liabilities	115	115
Total current liabilities	4,418	6,650
Deferred revenue - long term	111	162
Other liabilities	963	1,497
Total liabilities	5,492	8,309
Commitments and contingencies (Note 8)
Stockholders' equity:
Common stock	44	44
Additional paid-in capital	466,131	463,440
Accumulated deficit	(401,760)	(388,674)
Accumulated other comprehensive loss	(260)	(268)
Treasury stock	(2,741)	(2,741)
Total stockholders' equity	61,414	71,801	31,148
Total liabilities and stockholders' equity	$ 66,906	$ 80,110