Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended		404 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014
Cash flows from operating activities:
Net loss	$ (28,273)	$ (42,084)	$ (571,509)
Adjustments to reconcile net loss to net cash flows used in operating activities:
Depreciation and amortization	523	451	23,770
Amortization of premium on available-for-sale securities	519		519
Loss on abandonment of patents and disposal of property and equipment	6	196	3,232
Realized gain on sale of available-for-sale securities			(3,863)
Write-down of available-for-sale securities			17,001
Impairment charge on real estate owned			1,445
Stock-based compensation	4,342	1,671	47,542
Acquired in-process research and development			29,461
Increase in warrant valuation	3,251	26,906	92,246
Net increase in accounts receivable and other assets	(10,337)	(1,178)	(16,297)
Net increase (decrease) in accounts payable, accrued expenses and other liabilities	1,704	(955)	23,585
Net cash used in operating activities	(28,265)	(14,993)	(352,868)
Cash flows from investing activities:
Purchase of restricted investments		(7,250)	(7,897)
Purchase of property and equipment	(5,326)	(9)	(27,683)
Patent costs	(294)	(461)	(12,228)
Purchase of available-for-sale securities	(176,669)		(289,662)
Sale of available-for-sale securities			117,724
Acquisition costs			(2,389)
Net cash used in investing activities	(182,289)	(7,720)	(222,135)
Cash flows from financing activities:
Proceeds from exercise of options and warrants, and the sale of common stock, warrants, and partnership units, net of offering costs	2,713	2,993	625,258
Repayments of long-term debt	(23)	(22)	(542)
Other financing activities, net			(612)
Net cash provided by financing activities	2,690	2,971	624,104
Increase (decrease) in cash and cash equivalents	(207,864)	(19,742)	49,101
Cash and cash equivalents:
Beginning of period	256,965	187,661
End of period	49,101	167,919	49,101
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest	20	22	739
Supplemental Schedule of Noncash Investing Activities and Financing Activities:
Available-for-sale securities received in connection with the private offering			17,897
Issuance of common stock in satisfaction of warrants and other liabilities	3,044	1,022	114,092
Tenant improvements paid by landlord	593		6,807
Property and equipment included in accounts payable and other liabilities	3,533		3,533
Building
Supplemental Schedule of Noncash Investing Activities and Financing Activities:
Issuance of common stock			750
Assumption of long-term debt			2,200
Other Assets
Supplemental Schedule of Noncash Investing Activities and Financing Activities:
Issuance of common stock			8,075
Assumption of long-term debt			$ 2,124