Summary Of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2015

Summary Of Significant Accounting Policies [Abstract]

Summary Of The Amortized Costs And Fair Values Of Marketable Securities

	(In thousands)
	MARKETABLE SECURITIES
	Amortized Cost		Fair Value		Gross Unrealized Gains		Gross Unrealized Losses
December 31, 2015
Tax-exempt Municipal Bonds	$	20,129	$	20,115	$	4	$	18
Variable Rate Demand Notes		12,144		12,144		-		-
Total Marketable Securities	$	32,273	$	32,259	$	4	$	18
December 31, 2014
Tax-exempt Municipal Bonds	$	8,809	$	8,804	$	5	$	10
Variable Rate Demand Notes		13,600		13,600		-		-
Total Marketable Securities	$	22,409	$	22,404	$	5	$	10

Schedule Of Estimated Future Amortization Expense

Years ending December 31:	(In thousands)
2016	$	1,772
2017		3,699

Schedule Of Changes In Product Warranty

	(In thousands)
	Year Ended December 31
	2015		2014
Beginning balance January 1	$	377	$	568
Accruals during the period		677		296
Charges / payments made under the warranties		(567)		(487)
Balance December 31	$	487	$	377