Summary Of Significant Accounting Policies (Effect oO The Adoption Of ASC 606 On Financial Statements) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	[1]	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 84,222	$ 72,413	$ 160,043	$ 141,867
Income tax expense	(1,953)	(5,846)	(3,108)	(7,549)
Net income	4,999	19,032	8,045	22,063
Deferred income taxes	25,776		25,776			$ 24,747	$ 24,908
Deferred current revenue	7,341		7,341			9,495	9,850
Retained earnings	40,918		40,918			$ 32,873	$ 32,679
Balances Without Adoption of ASC 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Income tax expense	(1,955)		(3,039)
Net income	5,006		7,863
Deferred income taxes	25,845		25,845
Deferred current revenue	7,592		7,592
Retained earnings	40,736		40,736
Effect Of Change Higher/(Lower) [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Income tax expense	(2)		69
Net income	(7)		182
Deferred income taxes	(69)		(69)
Deferred current revenue	(251)		(251)
Retained earnings	182		182
Cinema [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	80,183	$ 67,443	152,438	$ 134,003
Cinema [Member] | Balances Without Adoption of ASC 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	80,192		152,187
Cinema [Member] | Effect Of Change Higher/(Lower) [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ (9)		$ 251

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