Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets
Equipment, leaseholds and intangible amortization, net	$ 176	$ 200
Operating lease liabilities	839	755
Inventory allowances	549	610
Accrued expenses	129	110
Warranty accrual	182	173
Deferred revenue	214	429
Federal and state tax credits	3,960	4,001
Federal and state net operating loss carry forwards	275	555
Share-based compensation	358	369
Other, net	113	114
Subtotal	6,795	7,316
Valuation allowance	(1,414)	(1,679)
Total deferred tax assets	5,381	5,637
Liabilities
Equipment, leaseholds and intangible amortization, net	251	287
Right-of-use assets (operating leases)	478	340
Inventory allowances	5	0
Other, net	50	18
Subtotal	784	645
Total deferred tax liabilities	$ 784	$ 645