Fair Value Measurements (Details 4) - Level 3 - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Gain on Sale of Investments		$ 8,669,000	$ 7,478,000	$ 2,532,000
Proceeds from Issuance of Warrants		(10,239,000)	(8,589,000)	(3,093,000)
Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants		324,000	821,000	1,407,000
Equity Warrants Transfers to Available For Sale Securities	$ (78,000)	$ (113,000)	(78,000)	1,182,000
Warrants Not Settleable in Cash, Fair Value Disclosure			$ 4,793,000	$ 5,161,000	$ 5,497,000