Investments (Cost And Estimated Fair Value Of Investments) (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 5,514,000	$ 5,341,000
Gross unrealized gain	2,671,000	3,639,000
Gross unrealized loss	(56,000)	(55,000)
Fair value, investments	8,129,000	8,925,000
Less cash equivalents, Carrying amount	771,000	1,102,000	5,634,000	5,476,000
Money Market [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	409,000	804,000
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Fair value, investments	409,000	804,000
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	101,000	200,000
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Fair value, investments	101,000	200,000
Treasury Bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	5,426,000	5,249,000
Gross unrealized gain	0	0
Gross unrealized loss	(2,000)	(1,000)
Fair value, investments	5,424,000	5,248,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	88,000	92,000
Gross unrealized gain	2,671,000	3,639,000
Gross unrealized loss	(54,000)	(54,000)
Fair value, investments	2,705,000	3,677,000
Debt and Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	6,024,000	6,345,000
Gross unrealized gain	2,671,000	3,639,000
Gross unrealized loss	(56,000)	(55,000)
Fair value, investments	8,639,000	9,929,000
Less Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Less cash equivalents, Carrying amount	510,000	1,004,000
Less cash equivalents, Fair value	$ 510,000	$ 1,004,000