Consolidated Balance Sheets - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 16,130,410	$ 21,373,273
Receivables	7,628	148,527
Prepaid expenses and other current assets	1,066,497	913,162
Current assets held for sale		81,182
Total current assets	17,204,535	22,516,144
Equipment and furnishings, net	42,893	44,326
Other assets	7,590	40,642
Non-current assets held for sale		324,853
Total assets	17,255,018	22,925,965
Current liabilities:
Accounts payable	887,835	1,234,762
Accrued expenses and other current liabilities	1,162,471	726,191
Current liabilities of discontinued operations		602,713
Total current liabilities	2,050,306	2,563,666
Commitments and contingencies
Stockholders' equity:
Common stock, $0.001 par value, 41,666,666 shares authorized; 33,637,501 and 33,637,501 shares issued and outstanding at December 31, 2019 and 2018, respectively	33,637	33,637
Additional paid-in capital	479,197,849	477,192,747
Accumulated deficit	(464,026,774)	(456,864,085)
Total stockholders' equity	15,204,712	20,362,299
Total liabilities and stockholders' equity	17,255,018	22,925,965
Series B Junior Participating Preferred Stock [Member]
Stockholders' equity:
Preferred Stock, value
Series A Junior Participating Preferred Stock [Member]
Stockholders' equity:
Preferred Stock, value
Series B Convertible Preferred Shares [Member]
Stockholders' equity:
Preferred Stock, value