Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net loss	$ (103,410)	$ (62,147)
Adjustments to reconcile net income to cash flows in operating activities:
Depreciation and amortization	2,571	1,483
Amortization of premium on available-for-sale securities and noncash interest	613	1,127
Loss on abandonment of patents	132	52
Stock-based compensation	20,086	9,929
Increase in warrant valuation		7,035
Changes in operating assets and liabilities, net:
Net increase in accounts receivable		(1,696)
Net decrease (increase) in other assets	8,695	(19,261)
Net increase in accounts payable, accrued expenses, deferred revenue and other liabilities	(566)	(4,291)
Net cash used in operations	(71,879)	(67,769)
Cash flows from investing activities:
Release and maturity of restricted investments		3,250
Purchase of property and equipment	(1,169)	(9,841)
Patent costs	(640)	(628)
Purchase of available-for-sale securities	(49,631)	(226,616)
Maturity of available-for-sale securities	98,650	48,669
Net cash from (used in) investing activities	47,210	(185,166)
Cash flows from financing activities:
Proceeds from borrowings, net of debt issuance costs	19,734
Repayments of long-term debt	(49)	(47)
Proceeds from exercise of options and warrants and the sale of common stock, net of offering costs	971	98,771
Net cash from financing activities	20,656	98,724
Decrease in cash and cash equivalents	(4,013)	(154,211)
Cash and cash equivalents:
Beginning of period	73,551	256,965
End of period	69,538	102,754
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	37	40
Supplemental schedule of non-cash investing activities and financing activities:
Issuance of common stock in satisfaction of warrants and other liabilities		6,215
Tenant improvement paid by Landlord		65
Property and equipment included in accrued expenses		422
Accrual for the debt issuance costs related to the senior secured term loan	540
Patent costs included in accrued expenses	170	$ 200
Capitalized interest	$ 99