STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net loss	$ (10,872)	$ (10,762)	$ (30,129)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,064	1,172	1,425
Amortization of premium/discount on marketable securities	1,873	1,117	1,130
Amortization of deferred gain on sale leaseback	(552)	(552)	(552)
Non-cash stock compensation	4,135	3,830	3,259
Loss on auction rate securities put option			5,074
Gain on auction rate securities	(113)	(20)	(4,362)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	3,676	(2,901)	1,357
Other long-term assets	191	(68)	(53)
Accounts payable and accrued expenses	(1,769)	(4,904)	4,476
Deferred revenue	(31,837)	(10,650)	(16,441)
Net cash used in operating activities	(34,204)	(23,738)	(34,816)
Cash flows from investing activities:
Purchases of marketable securities	(121,498)	(185,969)	(91,484)
Proceeds from sale or maturity of marketable securities	101,122	149,717	154,128
Purchases of property and equipment	(117)	(594)	(357)
Net cash provided by (used in) investing activities	(20,493)	(36,846)	62,287
Cash flows from financing activities:
Payment of notes payable			(44,400)
Proceeds from stock offering, net	56,256	46,756
Proceeds from stock option exercises and employee stock plan purchases	1,673	4,466	835
Net cash provided by (used in) financing activities	57,929	51,222	(43,565)
Net increase (decrease) in cash and cash equivalents	3,232	(9,362)	(16,094)
Cash and cash equivalents, beginning of period	11,095	20,457	36,551
Cash and cash equivalents, end of period	14,327	11,095	20,457
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION (IN THOUSANDS):
Interest paid	26	25	274
Taxes paid
Taxes refunded			$ 550