Investments (Cost And Estimated Fair Value Of Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 7,930	$ 6,614
Gross unrealized gain	0	1,238
Gross unrealized loss	58	54
Fair value, investments	7,872	7,798
Less cash equivalents, Carrying amount	569	1,190	$ 1,505
Money Market [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	246	510
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Fair value, investments	246	510
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	247	345
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Fair value, investments	247	345
Treasury Bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	7,876	6,542
Gross unrealized gain	0	0
Gross unrealized loss	4	0
Fair value, investments	7,872	6,542
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	54	72
Gross unrealized gain	0	1,238
Gross unrealized loss	54	54
Fair value, investments	0	1,256
Debt and Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	8,423	7,469
Gross unrealized gain	0	1,238
Gross unrealized loss	58	54
Fair value, investments	8,365	8,653
Less Cash and 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	493	855
Less cash equivalents, Fair value	$ 493	$ 855