Income Taxes, Operating Loss Carryforwards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Federal net operating loss carryforward	$ 10,600	$ 10,900
Federal research credit carryforwards	1,100	700
State net operating loss carryforward	2,100	2,200
State research credit carryforwards	0	0
Federal operating loss carryforwards, tax effect	200	4,800
State operating loss carryforwards, tax effect	100	1,400
Utilized federal research credit carryforwards	26	900
Income Tax Uncertainties [Abstract]
Reserves or related accruals for interest and penalty on income tax expense	0	0
Deferred tax assets relating to net operating loss carryforwards [Abstract]
Deferred tax assets relating to net operating loss carryforwards	12,780	$ 13,087
Rexahn stockholders [Member]
Deferred tax assets relating to net operating loss carryforwards [Abstract]
Deferred tax assets relating to net operating loss carryforwards	$ 10,300