Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Operating activities
Net loss	$ (30,094)	$ (22,849)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation of property and equipment	456	569
Stock-based compensation	3,415	1,970
Noncash interest expense	663	101
Changes in assets and liabilities:
Accounts receivable due from related party	216	11,638
Prepaids and other current assets	572	(374)
Other assets	1,935	(636)
Accounts payable	38	(446)
Other liabilities	1,337	(156)
Deferred revenue	(3,274)	(2,721)
Net cash used in operating activities	(24,736)	(12,904)
Investing activities
Purchases of property and equipment, net	(113)	(110)
Purchase of investments	(141,977)	(96,862)
Maturities of investments	82,860	93,677
Net cash used in investing activities	(59,230)	(3,295)
Financing activities
Proceeds from equipment financing		700
Payments on equipment financing obligations	(408)	(401)
Proceeds from exercise of stock options	317	127
Proceeds from issuance of convertible note		10,000
Proceeds from exercise of warrants		1,058
Proceeds from issuance of common stock	57,017
Net cash provided by financing activities	56,926	11,484
Net decrease in cash and cash equivalents	(27,040)	(4,715)
Cash and cash equivalents at beginning of period	40,155	12,056
Cash and cash equivalents at end of period	13,115	7,341
Supplemental disclosures of cash flow information
Cash paid for interest	113	68
Cash refund for income tax		(16)
Non-cash financing activity:
Issuance of common stock for settlement of convertible debt, including accrued interest	$ 10,215