Fair Value of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Marketable securities - mutual and exchange traded funds	$ 2,700	$ 3,998
Investments at fair value	10,345	1,020
Liabilities
Fair value of warrant liabilities	82	822
Quoted prices in active markets (Level 1) [Member]
Assets
Marketable securities - mutual and exchange traded funds	2,700	976
Investments at fair value
Liabilities
Fair value of warrant liabilities
Significant other observable inputs (Level 2) [Member]
Assets
Marketable securities - mutual and exchange traded funds		3,022
Investments at fair value
Liabilities
Fair value of warrant liabilities
Significant unobservable inputs (Level 3) [Member]
Assets
Marketable securities - mutual and exchange traded funds
Investments at fair value	10,345	1,020
Liabilities
Fair value of warrant liabilities		822
Hoth [Member]
Assets
Investments at fair value	9,214	1,020
Hoth [Member] | Significant unobservable inputs (Level 3) [Member]
Assets
Investments at fair value	9,214	$ 1,020
DatChat [Member]
Assets
Investments at fair value	1,000
DatChat [Member] | Significant unobservable inputs (Level 3) [Member]
Assets
Investments at fair value	1,000
Other investments [Member]
Assets
Investments at fair value	131
Other investments [Member] | Significant unobservable inputs (Level 3) [Member]
Assets
Investments at fair value	131
Liabilities
Fair value of warrant liabilities	$ 82