Debt (Summary Of Borrowings) (Details) - USD ($) $ in Thousands								9 Months Ended		12 Months Ended
		Mar. 13, 2020	Mar. 12, 2020	Mar. 06, 2020	Sep. 18, 2019	Oct. 12, 2018	Dec. 13, 2016	Sep. 30, 2020		Dec. 31, 2019
Debt Instrument [Line Items]
Contractual Facility								$ 289,876		$ 283,138
Balance Gross								274,140		209,218
Balance Net								271,623	[1]	207,012	[2]
Deferred financing costs, net								$ 2,500		$ 2,200
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								$ 26,451	[1]	$ 26,311	[2]
Stated Interest Rate								4.27%		5.94%
Effective Interest Rate								4.27%		5.94%
Bank Of America Credit Facility [Member]
Debt Instrument [Line Items]
Maturity Date				Mar. 06, 2023				Mar. 06, 2023		Mar. 06, 2023
Contractual Facility				$ 55,000				$ 55,000		$ 55,000
Balance Gross								49,200		33,500
Balance Net								$ 48,965	[1]	$ 33,445	[2]
Stated Interest Rate								3.15%		4.80%
Effective Interest Rate								3.15%		4.80%
Bank Of America Line Of Credit [Member]
Debt Instrument [Line Items]
Maturity Date				Mar. 06, 2023				Mar. 06, 2023		Mar. 06, 2023
Contractual Facility				$ 5,000				$ 5,000		$ 5,000
Balance Gross								5,000
Balance Net	[1]							$ 5,000
Stated Interest Rate								4.00%		4.80%
Effective Interest Rate								4.00%		4.80%
US Cinema 1, 2, 3 Term Loan [Member]
Debt Instrument [Line Items]
Maturity Date		Apr. 01, 2022						Apr. 01, 2022		Apr. 01, 2022
Contractual Facility		$ 25,000	$ 20,000					$ 24,768		$ 18,658
Balance Gross								24,768		18,658
Balance Net								$ 24,387	[1]	$ 18,532	[2]
Stated Interest Rate								4.25%		3.25%
Effective Interest Rate								4.25%		3.25%
Minetta And Orpheum Theatres Loan [Member]
Debt Instrument [Line Items]
Maturity Date	[3]							Nov. 01, 2023		Nov. 01, 2023
Contractual Facility						$ 7,500		$ 8,000	[3]	$ 8,000	[3]
Balance Gross	[3]							8,000		8,000
Balance Net	[3]							$ 7,908	[1]	$ 7,887	[2]
Stated Interest Rate	[3]							2.21%		3.74%
Effective Interest Rate	[3]							5.15%		5.15%
U.S. Corporate Office Term Loan [Member]
Debt Instrument [Line Items]
Maturity Date								Jan. 01, 2027		Jan. 01, 2027
Contractual Facility							$ 8,400	$ 9,246		$ 9,260
Balance Gross								9,246		9,260
Balance Net								$ 9,151	[1]	$ 9,153	[2]
Effective Interest Rate								4.61%		4.64%
Purchase Money Promissory Note [Member]
Debt Instrument [Line Items]
Maturity Date					Sep. 18, 2024			Sep. 18, 2024		Sep. 18, 2024
Contractual Facility								$ 2,883		$ 3,363
Balance Gross								2,883		3,363
Balance Net								$ 2,883	[1]	$ 3,363	[2]
Stated Interest Rate								5.00%		5.00%
Effective Interest Rate								5.00%		5.00%
Union Square Construction Financing [Member]
Debt Instrument [Line Items]
Maturity Date								Dec. 29, 2020		Dec. 29, 2020
Contractual Facility								$ 50,000		$ 50,000
Balance Gross								40,064		36,048
Balance Net								$ 40,009	[1]	$ 36,035	[2]
Stated Interest Rate								5.50%		6.02%
Effective Interest Rate								5.50%		6.02%
NAB Corporate Loan Facility [Member]
Debt Instrument [Line Items]
Maturity Date								Dec. 31, 2023	[4]	Dec. 31, 2023	[5]
Contractual Facility								$ 85,920	[4]	$ 84,360	[5]
Balance Gross								85,920	[4]	65,731	[5]
Balance Net								$ 85,722	[1],[4]	$ 65,541	[2],[5]
Stated Interest Rate								1.89%	[4]	1.77%	[5]
Effective Interest Rate								1.89%	[4]	1.77%	[5]
Westpac Bank Corporate Credit Facility [Member]
Debt Instrument [Line Items]
Maturity Date								Dec. 31, 2023	[4]	Dec. 31, 2023	[5]
Contractual Facility								$ 21,146	[4]	$ 21,584	[5]
Balance Gross								21,146	[4]	6,745	[5]
Balance Net								$ 21,147	[1],[4]	$ 6,745	[2],[5]
Stated Interest Rate								2.95%	[4]	3.05%	[5]
Effective Interest Rate								2.95%	[4]	3.05%	[5]
Minimum [Member] | U.S. Corporate Office Term Loan [Member]
Debt Instrument [Line Items]
Stated Interest Rate								4.44%		4.44%
Maximum [Member] | U.S. Corporate Office Term Loan [Member]
Debt Instrument [Line Items]
Stated Interest Rate								4.64%		4.64%

[1] Net of deferred financing costs amounting to $2.5 million.

[2] Net of deferred financing costs amounting to $2.2 million.

[3] The interest rate derivative associated with the Minetta & Orpheum loan provides for an effective fixed rate of 5.15%.

[4] The contractual facilities and outstanding balances of the foreign currency denominated borrowings were translated into U.S. dollars based on the applicable exchange rates as of September 30, 2020.

[5] The contractual facilities and outstanding balances of the foreign currency denominated borrowings were translated into U.S. dollars based on the applicable exchange rates as of December 31, 2019.