Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities
Net loss	$ (4,086)	$ (7,963)
Adjustments to reconcile net loss to net cash used in operating activities:
Amortization of patent portfolio	2,422	2,428
Non-cash registration rights penalty		700
Fair value adjustments for warrant liabilities		(40)
Stock-based compensation	87	3,396
Unrealized loss on marketable securities	57
Changes in assets and liabilities:
Marketable securities	582
Prepaid expenses and other assets	36	44
Accounts payable and accrued expenses	(54)	69
Accrued salaries and benefits	350	(156)
Accrued lease liabilities	(43)
Net cash used in operating activities	(694)	(1,522)
Cash flow from investing activities
Payment of accrued patent costs		(1,000)
Net cash used in investing activities		(1,000)
Cash flow from financing activities
Proceeds from issuance of common stock and warrants, net		3,900
Net cash provided by financing activities		3,900
Net decrease in cash and cash equivalents	(694)	1,378
Cash and cash equivalents, beginning of period	805	3,125
Cash and cash equivalents, end of period	111	4,503
Cash paid for interest and taxes
Non-cash investing and financing activities
Retirement of treasury stock		201
Conversion of preferred stock to common stock		$ 1