Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Operating activities:
Net loss	$ (33,332)	$ (22,870)
Adjustments to reconcile net loss to net cash (used for) provided by operating activities:
Share-based compensation	5,163	3,457
Depreciation and amortization	342	269
Amortization of debt discount and debt issuance costs	73	162
Deferred rent	8	25
Amortization of premium on short term investments, net	431	320
Realized gain on short-term investments	(2)	(23)
Change in operating assets and liabilities:
Receivables	15,245	(411)
Prepaids and other assets	(1,498)	(586)
Accounts payable	109	135
Accrued clinical liabilities	(1,035)	(265)
Accrued payroll and employee liabilities	(629)	(168)
Other accrued liabilities	696	104
Deferred revenue	(2,153)	(4,853)
Net cash used for operating activities	(16,582)	(24,704)
Investing activities:
Purchases of short-term investments	(150,460)	(90,486)
Proceeds from sale or maturity of short-term investments	96,011	35,738
Proceeds from sale of property and equipment	12	25
Purchases of property and equipment	(561)	(368)
Net cash used for investing activities	(54,998)	(55,091)
Financing activities:
Payments on long-term debt	(1,644)	(1,453)
Net proceeds from issuance of common stock	79,944	79,243
Net cash provided by financing activities	78,300	77,790
Net increase (decrease) in cash and cash equivalents	6,720	(2,005)
Cash and cash equivalents at beginning of period	15,926	11,562
Cash and cash equivalents at end of period	22,646	9,557
Supplemental disclosure of cash flow information:
Interest paid	174	342
Supplemental schedule of non-cash information:
Net unrealized loss on short-term investments	$ (31)	$ (2)