Investments (Cost And Estimated Fair Value Of Investments) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 7,480	$ 7,930
Gross unrealized gain	6	0
Gross unrealized loss	(54)	(58)
Fair value, investments	7,432	7,872
Less cash equivalents, Carrying amount	792	569	$ 2,435	$ 1,190
Money Market [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	240	246
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Fair value, investments	240	246
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	263	247
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Fair value, investments	263	247
Treasury Bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	7,426	7,876
Gross unrealized gain	6	0
Gross unrealized loss	0	(4)
Fair value, investments	7,432	7,872
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	54	54
Gross unrealized gain	0	0
Gross unrealized loss	(54)	(54)
Fair value, investments	0	0
Debt and Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	7,983	8,423
Gross unrealized gain	6	0
Gross unrealized loss	(54)	(58)
Fair value, investments	7,935	8,365
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	503	493
Less cash equivalents, Fair value	$ 503	$ 493