Condensed Consolidated Balance Sheets - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 19,377,824	$ 21,373,273
Receivables	9,383	148,527
Prepaid expenses and other current assets	465,019	913,162
Current assets held for sale	49,436	81,182
Total current assets	19,901,662	22,516,144
Equipment and furnishings, net	28,067	44,326
Other assets	12,649	40,642
Non-current assets held for sale		324,853
Total assets	19,942,378	22,925,965
Current liabilities:
Accounts payable	895,735	1,234,762
Accrued expenses and other current liabilities	937,740	726,191
Current liabilities of discontinued operations	21,879	602,713
Total liabilities	1,855,354	2,563,666
Commitments and contingencies
Stockholders' equity:
Preferred Stock, value
Common stock, $0.001 par value, 41,666,667 shares authorized; 33,637,501 shares issued and outstanding at June 30, 2019 and December 31, 2018	33,637	33,637
Additional paid-in capital	477,617,955	477,192,747
Accumulated deficit	(459,564,568)	(456,864,085)
Total stockholders' equity	18,087,024	20,362,299
Total liabilities and stockholders' equity	19,942,378	22,925,965
Series A Junior Participating Preferred Stock [Member]
Stockholders' equity:
Preferred Stock, value