Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Line Items]
U.S. Federal income tax benefit at federal statutory rate	21.00%	21.00%	35.00%
Reduction to deferred tax assest valuation allowance		$ 19,000,000
Expected refund for AMT credit carryforward	$ 200,000
Valuation allowance	34,978,000	34,726,000
Net operating loss carryforwards	142,674,000
Research and development tax credit carryforwards	2,479,000	2,438,000
Unrecognized tax benefits	0	0
Unrecognized tax benefits, interest and penalties	0	$ 0
Minimum [Member]
Income Tax Disclosure [Line Items]
U.S. Federal income tax benefit at federal statutory rate		21.00%
Expired [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	5,300,000
Indefinite [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 14,700,000