Summary Of Significant Accounting Policies (Summary Of The Amortized Costs And Fair Values Of Marketable Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
MARKETABLE SECURITIES, Amortized Cost	$ 32,273	$ 22,409
MARKETABLE SECURITIES, Fair Value	32,259	22,404
MARKETABLE SECURITIES, Gross Unrealized Gains	4	5
MARKETABLE SECURITIES, Gross Unrealized Losses	18	10
Tax-Exempt Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
MARKETABLE SECURITIES, Amortized Cost	20,129	8,809
MARKETABLE SECURITIES, Fair Value	20,115	8,804
MARKETABLE SECURITIES, Gross Unrealized Gains	4	5
MARKETABLE SECURITIES, Gross Unrealized Losses	18	10
Variable Rate Demand Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
MARKETABLE SECURITIES, Amortized Cost	12,144	13,600
MARKETABLE SECURITIES, Fair Value	$ 12,144	$ 13,600