Debt (Summary Of Notes Payable) (Details) - USD ($) $ in Thousands						3 Months Ended		12 Months Ended
		Jun. 26, 2017	Dec. 29, 2016	Dec. 13, 2016	Mar. 03, 2016	Mar. 31, 2018		Dec. 31, 2017
Debt Instrument [Line Items]
Contractual facility						$ 275,511		$ 271,732
Balance Gross						150,185		134,501
Balance Net						146,430	[1]	130,525	[2]
Deferred financing costs, net						$ 3,800		$ 4,000
Trust Preferred Securities [Member]
Debt Instrument [Line Items]
Maturity date						Apr. 30, 2027		Apr. 30, 2027
Contractual facility						$ 27,913		$ 27,913
Balance Gross						27,913		27,913
Balance Net						$ 27,564	[1]	$ 27,554	[2]
Stated interest rate						5.77%		5.38%
Effective interest rate	[3]					5.77%		5.38%
US Bank Of America Credit Facility [Member]
Debt Instrument [Line Items]
Maturity date						Nov. 28, 2019		Nov. 28, 2019
Contractual facility					$ 55,000	$ 55,000		$ 55,000
Balance Gross						31,000		31,000
Balance Net						$ 31,000	[1]	$ 31,000	[2]
Stated interest rate						4.88%		4.57%
Effective interest rate	[3]					4.88%		4.57%
US Bank Of America Line Of Credit [Member]
Debt Instrument [Line Items]
Maturity date						Oct. 31, 2019		Oct. 31, 2019
Contractual facility						$ 5,000		$ 5,000
Stated interest rate						4.84%		4.57%
Effective interest rate	[3]					4.84%		4.57%
US Bank Of America Digital Projector Loan [Member]
Debt Instrument [Line Items]
Maturity date						Dec. 28, 2019
Contractual facility						$ 4,031
Balance Gross						4,031
Balance Net	[1]					$ 4,031
Stated interest rate						5.00%
Effective interest rate	[3]					5.00%
US Cinema 1, 2, 3 Term Loan [Member]
Debt Instrument [Line Items]
Maturity date						Aug. 31, 2019	[4]	Sep. 01, 2019	[5]
Contractual facility						$ 19,396	[4]	$ 19,500	[5]
Balance Gross						19,396	[4]	19,500	[5]
Balance Net						$ 19,037	[1],[4]	$ 19,105	[2],[5]
Stated interest rate						3.25%	[4]	3.25%	[5]
Effective interest rate	[3]					3.25%	[4]	3.25%	[5]
Minetta And Orpheum Theatres Loan [Member]
Debt Instrument [Line Items]
Maturity date						Jun. 01, 2018	[4]	Jun. 01, 2018	[5]
Contractual facility						$ 7,500	[4]	$ 7,500	[5]
Balance Gross						7,500	[4]	7,500	[5]
Balance Net						$ 7,488	[1],[4]	$ 7,470	[2],[5]
Stated interest rate						4.44%	[4]	4.13%	[5]
Effective interest rate	[3]					4.44%	[4]	4.13%	[5]
U.S. Corporate Office Term Loan [Member]
Debt Instrument [Line Items]
Maturity date						Jan. 01, 2027	[4]	Jan. 01, 2027	[5]
Contractual facility				$ 8,400		$ 9,665	[4]	$ 9,719	[5]
Balance Gross						9,665	[4]	9,719	[5]
Balance Net						$ 9,531	[1],[4]	$ 9,582	[2],[5]
Effective interest rate	[3]					4.61%	[4]	4.61%	[5]
Debt increase		$ 1,500
Union Square Construction Financing [Member]
Debt Instrument [Line Items]
Maturity date						Dec. 29, 2019	[4]	Dec. 29, 2019	[5]
Contractual facility			$ 57,500			$ 57,500	[4]	$ 57,500	[5]
Balance Gross						9,155	[4]	8,000	[5]
Balance Net						$ 6,326	[1],[4]	$ 5,033	[2],[5]
Stated interest rate	[5]							5.81%
Effective interest rate	[3]					6.79%	[4]	5.81%	[5]
NAB Corporate Term Loan [Member]
Debt Instrument [Line Items]
Maturity date	[6]					Jun. 28, 2019
Contractual facility	[6]					$ 51,139
Balance Gross	[6]					41,525
Balance Net	[1],[6]					$ 41,453
Stated interest rate	[6]					3.78%
Effective interest rate	[3],[6]					3.78%
NAB Corporate Loan Facility [Member]
Debt Instrument [Line Items]
Maturity date	[7]							Jun. 30, 2019
Contractual facility	[7]							$ 51,970
Balance Gross	[7]							30,869
Balance Net	[2],[7]							$ 30,781
Stated interest rate	[7]							3.66%
Effective interest rate	[3],[7]							3.66%
Westpac Bank Corporate (General/Non-construction) Credit Facility [Member]
Debt Instrument [Line Items]
Maturity date						Dec. 31, 2019	[6]	Dec. 31, 2019	[7]
Contractual facility						$ 25,337	[6]	$ 24,850	[7]
Stated interest rate						3.70%	[6]	3.70%	[7]
Effective interest rate	[3]					3.70%	[6]	3.70%	[7]
Westpac Bank Corporate (Construction) Credit Facility [Member]
Debt Instrument [Line Items]
Maturity date						Dec. 31, 2018	[6]	Dec. 31, 2018	[7]
Contractual facility						$ 13,030	[6]	$ 12,780	[7]
Stated interest rate						3.70%	[6]	3.70%	[7]
Effective interest rate	[3]					3.70%	[6]	3.70%	[7]
Minimum [Member] | U.S. Corporate Office Term Loan [Member]
Debt Instrument [Line Items]
Stated interest rate						4.44%		4.44%
Minimum [Member] | Union Square Construction Financing [Member]
Debt Instrument [Line Items]
Stated interest rate						6.06%
Maximum [Member] | U.S. Corporate Office Term Loan [Member]
Debt Instrument [Line Items]
Stated interest rate						4.64%		4.64%
Maximum [Member] | Union Square Construction Financing [Member]
Debt Instrument [Line Items]
Stated interest rate						11.88%

[1] Net of deferred financing costs amounting to $3.8 million.

[2] Net of deferred financing costs amounting to $4.0 million.

[3] Both interest rate derivatives associated with the Trust Preferred Securities and Bank of America Credit Facility expired in October 2017 so the effective interest rate no longer applies as of December 31, 2017.

[4] The loan for our Minetta & Orpheum Theatres was obtained from Santander Bank. The term loan for our Cinema 1,2,3 Theatre was refinanced during the third quarter of 2016 with Valley National Bank. The term loan, which is collateralized by our new U.S Corporate Headquarters office building, was obtained with Citizens Asset Finance, Inc. In December 2016, we completed the negotiation of the construction financing for our Union Square redevelopment project, $8.0 million of which was advanced from the total construction loan limit of $57.5 million on December 29, 2016. As of March 31, 2018 an additional $1.2 million had been advanced.

[5] The loan for our Minetta & Orpheum Theatres was obtained from Santander Bank. The term loan for our Cinema 1,2,3 Theatre was refinanced during the third quarter of 2016 with Valley National Bank. The term loan, which is collateralized by our new U.S Corporate Headquarters office building, was obtained with Citizens Asset Finance, Inc.. In December 2016, we completed the negotiation of the construction financing for our Union Square redevelopment project, $8.0 million of which was advanced from the total construction loan limit of $57.5 million on December 29, 2016. As of December 31, 2017 no further advances had been made under this financing agreement.

[6] The contractual facilities and outstanding balances of the FC-denominated borrowings were translated into U.S. dollars based on the applicable exchange rates as of March 31, 2018.

[7] The contractual facilities and outstanding balances of the FC-denominated borrowings were translated into U.S. dollars based on the applicable exchange rates as of December 31, 2016.