Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended		9 Months Ended			9 Months Ended		3 Months Ended	12 Months Ended				9 Months Ended									9 Months Ended		12 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 segment years	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 American Multi-Cinema, Inc. [Member]	Sep. 30, 2011 American Multi-Cinema, Inc. [Member]	Jun. 28, 2012 AMCE [Member]	Mar. 29, 2012 AMCE [Member]	Mar. 31, 2011 AMCE [Member]	Mar. 31, 2010 AMCE [Member]	May 20, 2012 AMCE [Member]	Sep. 30, 2012 Share Options [Member] years	Sep. 30, 2011 Share Options [Member] years	Sep. 30, 2012 Share Options [Member] Non-Employee Trustees [Member] years	Sep. 30, 2012 Restricted Stock [Member] Employee [Member]	Sep. 30, 2011 Restricted Stock [Member] Employee [Member]	Sep. 30, 2012 Restricted Share Units [Member]	Sep. 30, 2012 Restricted Share Units [Member] Non-Employee Trustees [Member]	Sep. 30, 2011 Restricted Share Units [Member] Non-Employee Trustees [Member]	Sep. 30, 2012 ONTARIO Entertainment Retail Center Properties [Member] properties	Sep. 30, 2012 ONTARIO Four Entertainment Retail Centers [Member]	Sep. 30, 2011 ONTARIO Four Entertainment Retail Centers [Member]	Dec. 31, 2011 ONTARIO Four Entertainment Retail Centers [Member]	Sep. 30, 2012 Minimum [Member] Share Options [Member]	Sep. 30, 2012 Maximum [Member] Share Options [Member]
Operating Segments
Number of reportable operating segments (in reportable segments)			4
Rental Properties [Abstract]
Estimated useful live of buildings (in years)			40
Estimated useful lives of furniture, fixtures and equipment minimum (in years)			3
Estimated useful lives of furniture, fixtures and equipment maximum (in years)			25
Revenue Recognition [Abstract]
Percentage rents			$ 1,089,000	$ 1,028,000
Lease termination fees			0	1,000,000
Concentrations of Risk [Abstract]
Percent of megaplex theatre rental leased by AMC						31.00%
Rental revenue	61,049,000	56,849,000	178,543,000	168,255,000		73,100,000	79,200,000
Percentage of lease revenue in total revenue						31.00%	35.00%															13.00%	14.00%
Total assets	2,915,372,000		2,915,372,000		2,733,995,000				3,600,000,000	3,700,000,000
Total liabilities	1,448,518,000		1,448,518,000		1,235,892,000				3,500,000,000	3,400,000,000
Total stockholders' equity	1,466,524,000		1,466,524,000		1,470,049,000				154,000,000	360,000,000
Net earnings (loss)	34,151,000	35,552,000	92,322,000	77,286,000				(18,200,000)	(82,000,000)	122,900,000	(69,800,000)
Business acquisition purchase price												(2,600,000,000)
Number of weeks in lessee's fiscal year									P52W	P52W	P52W
Total revenue	82,836,000	75,974,000	239,625,000	223,974,000																		32,000,000	32,000,000
Number of real estate properties (in properties)																					4
Net assets of wholly owned subsidiaries																						148,700,000		144,600,000
Wholly owned subsidiaries percentage in net assets																						10.00%		10.00%
Share-based Compensation [Abstract]
Share based compensation			4,416,000	4,211,000
Share based compensation, future vesting period minimum (in years)			three										4			3
Share based compensation, future vesting period maximum (in years)			five										5			5
Range of settlement date for shares for non-employee trustee from grant date, minimum (in years)			1 year															1 year
Number of years from date of grant that share options may not be exercised															1
Stock-option expense													709,000	562,000
Share based compensation, risk-free interest rate minimum													1.10%	2.50%
Share based compensation, risk-free interest rate maximum													1.40%	3.10%
Share based compensation, dividend yield														6.40%											6.30%	6.70%
Share-based compensation, volatility factors in the expected market price, minimum													51.30%
Share-based compensation, volatility factors in the expected market price, maximum													51.40%
Share-based compensation, volatility factors in the expected market price														39.80%
Share-based compensation, expected forfeiture rate													0.25%	0.00%
Share based compensation, expected life (in years)													6	8
Share based compensation expense related to employees and trustees			1,400,000													3,300,000	3,200,000		372,000	367,000
Gain (Loss) On Lease Termination Within Discontinued Operations				$ 1,000,000