Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets
Equipment, leaseholds and intangible amortization, net	$ 217	$ 352
Inventory allowances	563	783
Accrued expenses	139	221
Warranty accrual	165	272
Deferred revenue	155	181
Accounts receivable allowance	102	188
Federal and state tax credits	3,818	3,624
Federal and state net operating loss carry forwards	2,237	2,801
Foreign net operating loss carry forwards	0	463
Stock based compensation	289	381
Other, net	50	79
Subtotal	7,735	9,345
Valuation allowance	(1,606)	(1,086)
Total deferred tax assets	6,129	8,259
Liabilities
Equipment, leaseholds and intangible amortization, net	387	395
Inventory allowances	0	21
Earnings of foreign subsidiary	0	2,520
Subtotal	387	2,936
Total deferred tax liabilities	$ 387	$ 2,936