Fair Value of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Assets
Marketable securities - mutual and exchange traded funds	$ 3,409	$ 3,998
Investments at fair value	2,725	1,020
Liabilities
Fair value of warrant liabilities	262	822
Quoted prices in active markets (Level 1) [Member]
Assets
Marketable securities - mutual and exchange traded funds
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	3,409	3,998
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	2,725	1,020	$ 1,020
Liabilities
Fair value of warrant liabilities	262	822
Hoth [Member]
Assets
Investments at fair value	1,700		$ 1,020
Hoth [Member] | Significant unobservable inputs (Level 3) [Member]
Assets
Investments at fair value	1,700	$ 1,020
TheBit Daily LLC [Member]
Assets
Investments at fair value	25
TheBit Daily LLC [Member] | Significant unobservable inputs (Level 3) [Member]
Assets
Investments at fair value	25
DatChat [Member]
Assets
Investments at fair value	1,000
DatChat [Member] | Significant unobservable inputs (Level 3) [Member]
Assets
Investments at fair value	$ 1,000