Investments (Cost And Estimated Fair Value Of Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 2,034	$ 3,054
Gross unrealized gain	2	2
Gross unrealized loss	0	0
Fair value	2,036	3,056
Less cash equivalents, Carrying amount	7,646	6,713
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	1,377	1,520
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Fair value	1,377	1,520
Treasury Bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	7,922	8,000
Gross unrealized gain	32	0
Gross unrealized loss	0	0
Fair value	7,954	8,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	54	54
Gross unrealized gain	2	2
Gross unrealized loss	0	0
Fair value	56	56
Debt and Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	9,353	9,574
Gross unrealized gain	34	2
Gross unrealized loss	0	0
Fair value	9,387	9,576
Less Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized gain	32	0
Gross unrealized loss	0	0
Less cash equivalents, Carrying amount	7,319	6,520
Less cash equivalents, Fair value	$ 7,351	$ 6,520