Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Operating Activities:
Net loss	$ (12,996)	$ (19,837)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	334	319
Amortization of premium/discount on marketable securities	490	786
Stock-based compensation	2,607	3,929
Changes in operating assets and liabilities:
Interest receivable	132	(172)
Accounts receivable	(2,322)	(1,015)
Prepaid expenses and other assets	(268)	(356)
Accounts payable and accrued liabilities	(2,867)	(3,005)
Accrued compensation and employee benefits	(378)	(355)
Deferred revenues	12,122	277
Net cash used in operating activities	(3,146)	(19,429)
Investing Activities:
Purchases of investments	(47,505)	(78,884)
Maturities of investments	52,120	44,556
Purchases of property and equipment	(263)	(196)
Net cash provided by (used in) investing activities	4,352	(34,524)
Financing Activities:
Proceeds from issuance of common stock	504	51,590
Net cash provided by financing activities	504	51,590
Net increase/ (decrease) in cash and cash equivalents	1,710	(2,363)
Cash and cash equivalents, beginning of period	16,766	10,784
Cash and cash equivalents, end of period	$ 18,476	$ 8,421