Summary Of Significant Accounting Policies (Effect of the Adoption of ASC 606 on Financial Statements) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	[1]	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 75,822	$ 69,454
Income tax expense	(1,155)	(1,703)
Net income	3,047	3,029
Deferred income taxes	24,834			$ 24,747	$ 24,908
Deferred current revenue	8,276			9,496	9,850
Retained earnings	35,920			$ 32,873	$ 32,679
Balances Without Adoption of ASC 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Income tax expense	(1,084)
Net income	2,858
Deferred income taxes	24,905
Deferred current revenue	8,536
Retained earnings	35,731
Effect Of Change Higher/(Lower) [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Income tax expense	(71)
Net income	189
Deferred income taxes	(71)
Deferred current revenue	(260)
Retained earnings	189
Cinema [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	72,255	$ 66,560
Cinema [Member] | Balances Without Adoption of ASC 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	71,995
Cinema [Member] | Effect Of Change Higher/(Lower) [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 260

[1] Certain prior year balances have been reclassified to conform to the 2018 presentation (see Note 2 - Summary of Significant Accounting Policies - Reclassifications).