Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net loss	$ (6,476)	$ (51,465)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of patent portfolio	2,135	6,317
Change in fair value of warrant liabilities	(2,257)	(269)
Stock-based compensation	562	371
Depreciation expenses	3	1
Realized loss on marketable securities	95
Unrealized (gain) loss on marketable securities	243	(19)
Impairment of goodwill and intangible assets	2,713	40,600
Changes in assets and liabilities:
Prepaid expenses and other assets	195	(223)
Accounts payable and accrued expenses	(261)	(344)
Accrued salaries and benefits	(199)	316
Deferred revenue	3,497	268
Accrued lease liabilities	(180)	(173)
Net cash provided by (used in) operating activities	70	(4,620)
Cash flows from investing activities
Purchase of marketable securities	(18,035)	(7,994)
Purchase of property and equipment	(4)	(2)
Sale of marketable securities	15,065	8,121
Net cash (used in) provided by investing activities	(2,974)	125
Cash flows from financing activities
Proceeds from issuance of common stock and warrants in July Financing, net		1,322
Proceeds from issuance of common stock and preferred stock in December Offering, net		3,445
Cash paid for cancellation of fractional shares of common stock	(4)
Cash from issuance common stock, net of offering cost	2,140
Proceeds from exercise of warrants	760
Redemption of Series I redeemable convertible preferred stock		(935)
Net cash provided by financing activities	2,896	3,832
Net decrease in cash and cash equivalents	(8)	(663)
Cash and cash equivalents, beginning of period	142	805
Cash and cash equivalents, end of period	134	142
Cash paid for interest and taxes
Non-cash investing and financing activities
Extinguishment of Series H Convertible Preferred Stock in connection with license agreement	31,480	4,766
Recognition of deferred revenue in connection with license agreement	414	281
Extinguishment of Series I Convertible Preferred Stock in connection with license agreement		$ 5,000