Investments (Cost And Estimated Fair Value Of Investments) (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 5,340,000	$ 5,341,000
Gross unrealized gain	3,099,000	3,639,000
Gross unrealized loss	(54,000)	(55,000)
Fair value, investments	8,385,000	8,925,000
Less cash equivalents, Carrying amount	825,000	1,102,000	5,581,000	5,476,000
Money Market [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	632,000	804,000
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Fair value, investments	632,000	804,000
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	75,000	200,000
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Fair value, investments	75,000	200,000
Treasury Bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	5,249,000	5,249,000
Gross unrealized gain	1,000	0
Gross unrealized loss	0	(1,000)
Fair value, investments	5,250,000	5,248,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	91,000	92,000
Gross unrealized gain	3,098,000	3,639,000
Gross unrealized loss	(54,000)	(54,000)
Fair value, investments	3,135,000	3,677,000
Debt and Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	6,047,000	6,345,000
Gross unrealized gain	3,099,000	3,639,000
Gross unrealized loss	(54,000)	(55,000)
Fair value, investments	9,092,000	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	707,000	1,004,000
Less cash equivalents, Fair value	$ 707,000	$ 1,004,000