Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2014

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]

Schedule of Fair Values of Financial Assets and Liabilities by Levels [Table Text Block]

		As of September 30, 2014
(Amounts in thousands)		Total		Level 1		Level 2		Level 3
Marketable securities		$	184,154	$	184,154	$	-	$	-
Real Estate Fund investments (75% of which is attributable to
	noncontrolling interests)		495,392		-		-		495,392
Deferred compensation plan assets (included in other assets)			113,549		50,366		-		63,183
	Total assets	$	793,095	$	234,520	$	-	$	558,575
Mandatorily redeemable instruments (included in other liabilities)		$	55,096	$	55,096	$	-	$	-
Interest rate swap (included in other liabilities)			26,036		-		26,036		-
	Total liabilities	$	81,132	$	55,096	$	26,036	$	-
		As of December 31, 2013
(Amounts in thousands)		Total		Level 1		Level 2		Level 3
Marketable securities		$	191,917	$	191,917	$	-	$	-
Real Estate Fund investments (75% of which is attributable to
	noncontrolling interests)		667,710		-		-		667,710
Deferred compensation plan assets (included in other assets)			116,515		47,733		-		68,782
	Total assets	$	976,142	$	239,650	$	-	$	736,492
Mandatorily redeemable instruments (included in other liabilities)		$	55,097	$	55,097	$	-	$	-
Interest rate swap (included in other liabilities)			31,882		-		31,882		-
	Total liabilities	$	86,979	$	55,097	$	31,882	$	-

Non-financial Assets Measured at Fair Value on a Nonrecurring Basis [Table Text Block]

			As of September 30, 2014
(Amounts in thousands)			Total		Level 1		Level 2		Level 3
	Investment in Suffolk Downs		$	1,328	$	-	$	-	$	1,328
			As of December 31, 2013
(Amounts in thousands)			Total		Level 1		Level 2		Level 3
	Real estate assets		$	354,351	$	-	$	-	$	354,351
	Investment in Toys "R" Us			83,224		-		-		83,224
		Total assets	$	437,575	$	-	$	-	$	437,575

Schedule Of Carrying Amounts And Fair Values Of Financial Instruments [Table Text Block]

			As of September 30, 2014				As of December 31, 2013
			Carrying		Fair		Carrying		Fair
(Amounts in thousands)			Amount		Value		Amount		Value
	Cash equivalents		$	1,361,305	$	1,361,000	$	295,000	$	295,000
	Mortgage and mezzanine loans receivable			17,085		17,000		170,972		171,000
			$	1,378,390	$	1,378,000	$	465,972	$	466,000
	Debt:
		Mortgages payable	$	9,273,212	$	9,192,000	$	8,331,993	$	8,104,000
		Senior unsecured notes		1,791,987		1,840,000		1,350,855		1,402,000
		Revolving credit facility debt		88,138		88,000		295,870		296,000
			$	11,153,337	$	11,120,000	$	9,978,718	$	9,802,000

Real Estate Fund [Member]

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]

Fair Value Inputs, Assets, Quantitative Information [Table Text Block]

			Weighted Average
			(based on fair
Unobservable Quantitative Input		Range	value of investments)
	Discount rates	12.0% to 17.5%	13.7%
	Terminal capitalization rates	5.0% to 6.3%	5.8%

Summary of Changes in Level 3 Plan Assets [Table Text Block]

	Real Estate Fund Investments				Real Estate Fund Investments
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(Amounts in thousands)		2014		2013	2014		2013
Beginning balance	$	549,091	$	622,124	$	667,710	$	600,786
Purchases		725		7,406		3,392		38,299
Dispositions / Distributions		(74,755)		(14,184)		(307,268)		(70,848)
Net unrealized gains		18,333		12,367		55,221		59,476
Net realized gains		51,584		8,184		126,653		8,184
Previously recorded unrealized gains		(49,586)		-		(50,316)		-
Other, net		-		93		-		93
Ending balance	$	495,392	$	635,990	$	495,392	$	635,990

Deferred Compensation Plan Assets [Member]

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]

Summary of Changes in Level 3 Plan Assets [Table Text Block]

	Deferred Compensation Plan Assets				Deferred Compensation Plan Assets
	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(Amounts in thousands)		2014		2013	2014		2013
Beginning balance	$	64,609	$	66,502	$	68,782	$	62,631
Purchases		1,377		880		10,936		4,027
Sales		(4,917)		(873)		(21,296)		(5,318)
Realized and unrealized gain (loss)		927		(42)		2,901		4,094
Other, net		1,187		58		1,860		1,091
Ending balance	$	63,183	$	66,525	$	63,183	$	66,525