Debt (Summary Of Notes Payable) (Details) - USD ($)					9 Months Ended		12 Months Ended
		Dec. 29, 2016	Dec. 13, 2016	Mar. 03, 2016	Sep. 30, 2018		Dec. 31, 2017
Debt Instrument [Line Items]
Contractual Facility					$ 268,176,000		$ 271,732,000
Balance Gross					167,090,000		134,501,000
Balance Net					163,990,000	[1]	130,525,000	[2]
Deferred financing costs, net					$ 3,100,000		$ 4,000,000
Trust Preferred Securities [Member]
Debt Instrument [Line Items]
Maturity date					Apr. 30, 2027		Apr. 30, 2027
Contractual Facility					$ 27,913,000		$ 27,913,000
Balance Gross					27,913,000.00		27,913,000
Balance Net					$ 27,584,000.00	[1]	$ 27,554,000	[2]
Stated Interest Rate					6.37%		5.38%
Effective interest rate					6.37%	[3]	5.38%	[4]
US Bank Of America Credit Facility [Member]
Debt Instrument [Line Items]
Maturity date					Nov. 28, 2019		Nov. 28, 2019
Contractual Facility				$ 55,000,000	$ 55,000,000		$ 55,000,000
Balance Gross					34,000,000.00		31,000,000
Balance Net					$ 34,000,000.00	[1]	$ 31,000,000	[2]
Stated Interest Rate					4.74%		4.57%
Effective interest rate					4.74%	[3]	4.57%	[4]
US Bank Of America Line Of Credit [Member]
Debt Instrument [Line Items]
Maturity date					Oct. 31, 2019		Oct. 31, 2019
Contractual Facility					$ 5,000,000		$ 5,000,000
Balance Gross					1,500,000.00
Balance Net	[1]				$ 1,500,000.00
Stated Interest Rate					5.17%		4.57%
Effective interest rate					5.17%	[3]	4.57%	[4]
US Bank Of America Digital Projector Loan [Member]
Debt Instrument [Line Items]
Maturity date					Dec. 28, 2019
Contractual Facility					$ 3,221,000
Balance Gross					3,221,000.00
Balance Net	[1]				$ 3,221,000.00
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					Sep. 01, 2019		Sep. 01, 2019
Contractual Facility					$ 19,191,000		$ 19,500,000
Balance Gross					19,191,000.00		19,500,000
Balance Net					$ 18,906,000.00	[1]	$ 19,105,000	[2]
Stated Interest Rate					3.25%		3.25%
Effective interest rate					3.25%	[3]	3.25%	[4]
Minetta And Orpheum Theatres Loan [Member]
Debt Instrument [Line Items]
Maturity date					Nov. 01, 2023		Jun. 01, 2018
Contractual Facility					$ 7,500,000		$ 7,500,000
Balance Gross					7,500,000.00		7,500,000
Balance Net					$ 7,476,000.00	[1]	$ 7,470,000	[2]
Stated Interest Rate					4.88%		4.13%
Effective interest rate					4.88%	[3]	4.13%	[4]
U.S. Corporate Office Term Loan [Member]
Debt Instrument [Line Items]
Maturity date					Jan. 01, 2027		Jan. 01, 2027
Contractual Facility			$ 8,400,000		$ 9,552,000		$ 9,719,000
Balance Gross					9,552,000.00		9,719,000
Balance Net					$ 9,426,000.00	[1]	$ 9,582,000	[2]
Effective interest rate					4.61%	[3]	4.61%	[4]
Union Square Construction Financing [Member]
Debt Instrument [Line Items]
Maturity date					Dec. 29, 2019		Dec. 29, 2019
Contractual Facility		$ 57,500,000			$ 57,500,000		$ 57,500,000
Balance Gross					25,852,000.00		8,000,000
Balance Net					$ 23,560,000.00	[1]	$ 5,033,000	[2]
Stated Interest Rate							5.81%
Effective interest rate					8.17%	[3]	5.81%	[4]
NAB Corporate Term Loan [Member]
Debt Instrument [Line Items]
Maturity date					Dec. 31, 2019
NAB Corporate Loan Facility [Member]
Debt Instrument [Line Items]
Maturity date					Dec. 31, 2019	[5]	Jun. 30, 2019	[6]
Contractual Facility					$ 48,133,000	[5]	$ 51,970,000	[6]
Balance Gross					38,361,000.00	[5]	30,869,000	[6]
Balance Net					$ 38,317,000.00	[1],[5]	$ 30,781,000	[2],[6]
Stated Interest Rate					2.88%	[5]	3.66%	[6]
Effective interest rate					2.88%	[3],[5]	3.66%	[4],[6]
Westpac Bank Corporate (General/Non-construction) Credit Facility [Member]
Debt Instrument [Line Items]
Maturity date					Dec. 31, 2019	[5]	Dec. 31, 2019	[6]
Contractual Facility					$ 23,223,000	[5]	$ 24,850,000	[6]
Stated Interest Rate					3.80%	[5]	3.70%	[6]
Effective interest rate					3.80%	[3],[5]	3.70%	[4],[6]
Westpac Bank Corporate (Construction) Credit Facility [Member]
Debt Instrument [Line Items]
Maturity date					Dec. 31, 2018	[5]	Dec. 31, 2018	[6]
Contractual Facility					$ 11,943,000	[5]	$ 12,780,000	[6]
Stated Interest Rate					3.80%	[5]	3.70%	[6]
Effective interest rate					3.80%	[3],[5]	3.70%	[4],[6]
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					6.52%
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					12.22%

[1] Net of deferred financing costs amounting to $3.1 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 September 30, 2018.

[4] 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.

[5] 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 September 30, 2018.

[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 December 31, 2017.