Consolidated Statements of Changes in Equity (USD $) In Thousands, unless otherwise specified	Total	Real Estate Fund [Member]	All Other Except Real Estate Fund [Member]	Preferred Shares	Common Shares	Additional Capital	Earnings Less Than Distributions	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interests	Non-controlling Interests Real Estate Fund [Member]	Non-controlling Interests All Other Except Real Estate Fund [Member]
Beginning balance, Value at Dec. 31, 2010	$ 6,830,405			$ 783,088	$ 7,317	$ 6,932,728	$ (1,480,876)	$ 73,453	$ 514,695
Beginning balance, Shares at Dec. 31, 2010				32,340	183,662
Net income	684,088						662,302		21,786
Dividends on common shares, Value	(508,745)						(508,745)
Dividends on preferred shares, Value	(65,694)						(65,694)
Issuance of preferred shares, Shares				9,850
Issuance of preferred shares, Value	238,842			238,842
Common shares issued:
Upon redemption of Class A units, at redemption value, Shares					798
Upon redemption of Class A units, at redemption value, Value	64,830				32	64,798
Under Omnibus share plan, Shares					590
Under Omnibus share plan, Value	10,439				23	23,705	(13,289)
Under dividend reinvestment plan, Shares					21
Under dividend reinvestment plan, Value	1,772				1	1,771	0
Contributions:
Contributions		203,407	778							203,407	778
Distribution:
Distributions		(49,422)	(15,604)							(49,422)	(15,604)
Conversion Of Series A preferred shares to common shares, Shares				(3)	5
Conversion of Series A preferred shares to common shares, Value	0			(165)		165
Deferred compensation shares and options, Shares					4
Deferred compensation shares and options, Value	10,085				0	10,608	(523)
Change in unrealized net gain (loss) on securities available-for-sale	41,657							41,657
Non-cash impairment loss on J.C. Penney common shares	0
Amounts reclassified related to sale of available-for-sale securities	(5,020)							(5,020)
Pro rata share of other comprehensive (loss) income of nonconsolidated subsidiaries	12,859							12,859
Change in value of interest rate swap	(43,704)							(43,704)
Adjustments to carry redeemable Class A units at redemption value	98,092					98,092
Redeemable noncontrolling interests' share of above adjustments	(271)							(271)
Preferred unit and share redemptions	5,000
Other	(347)			(105)		(4,609)	5,121	(5,245)	4,491
Ending balance, Value at Dec. 31, 2011	7,508,447			1,021,660	7,373	7,127,258	(1,401,704)	73,729	680,131
Ending balance, Shares at Dec. 31, 2011				42,187	185,080
Net income	649,278						617,260		32,018
Dividends on common shares, Value	(699,318)						(699,318)
Dividends on preferred shares, Value	(76,937)						(76,937)
Issuance of preferred shares, Shares				12,000
Issuance of preferred shares, Value	290,971			290,971
Redemption of preferred shares, Shares				(3,000)
Redemption of preferred shares, Value	(72,248)			(72,248)
Common shares issued:
Upon redemption of Class A units, at redemption value, Shares					1,121
Upon redemption of Class A units, at redemption value, Value	89,762				45	89,717
Under Omnibus share plan, Shares					434
Under Omnibus share plan, Value	(6,850)				18	9,521	(16,389)
Under dividend reinvestment plan, Shares					29
Under dividend reinvestment plan, Value	2,307				1	2,306
Upon acquisition of real estate, Shares					64
Upon acquisition of real estate, Value	5,124				3	5,121
Contributions:
Contributions		195,029	18,103							195,029	18,103
Distribution:
Distributions		(48,138)	(59)							(48,138)	(59)
Conversion Of Series A preferred shares to common shares, Shares				(2)	3
Conversion of Series A preferred shares to common shares, Value	0			(105)	0	105
Deferred compensation shares and options, Shares					4
Deferred compensation shares and options, Value	13,054				0	13,527	(473)
Change in unrealized net gain (loss) on securities available-for-sale	(283,649)							(283,649)
Non-cash impairment loss on J.C. Penney common shares	224,937							224,937
Amounts reclassified related to sale of available-for-sale securities	(3,582)							(3,582)
Pro rata share of other comprehensive (loss) income of nonconsolidated subsidiaries	(31,758)							(31,758)
Change in value of interest rate swap	(5,659)							(5,659)
Adjustments to carry redeemable Class A units at redemption value	(52,117)					(52,117)
Redeemable noncontrolling interests' share of above adjustments	6,707							6,707
Preferred unit and share redemptions	8,948						8,948
Consolidation of a partially owned entity	176,132								176,132
Other	(4,340)			0		0	(4,662)	329	(7)
Ending balance, Value at Dec. 31, 2012	7,904,144			1,240,278	7,440	7,195,438	(1,573,275)	(18,946)	1,053,209
Ending balance, Shares at Dec. 31, 2012				51,185	186,735
Net income	539,923						475,971		63,952
Dividends on common shares, Value	(545,913)						(545,913)
Dividends on preferred shares, Value	(82,807)						(82,807)
Issuance of preferred shares, Shares				12,000
Issuance of preferred shares, Value	290,306			290,306
Redemption of preferred shares, Shares				(10,500)
Redemption of preferred shares, Value	(253,269)			(253,269)			0
Common shares issued:
Upon redemption of Class A units, at redemption value, Shares					299
Upon redemption of Class A units, at redemption value, Value	25,317				12	25,305
Under Omnibus share plan, Shares					104
Under Omnibus share plan, Value	5,808				23	5,892	(107)
Under dividend reinvestment plan, Shares					22
Under dividend reinvestment plan, Value	1,851				1	1,850
Upon acquisition of real estate, Shares					128
Upon acquisition of real estate, Value	11,461				5	11,456
Contributions:
Contributions		28,078	15,886							28,078	15,886
Distribution:
Distributions		(47,268)	(133,153)							(47,268)	(133,153)
Conversion Of Series A preferred shares to common shares, Shares				(2)	3
Conversion of Series A preferred shares to common shares, Value	0			(90)	0	90
Deferred compensation shares and options, Shares					(6)
Deferred compensation shares and options, Value	9,270				(12)	9,589	(307)
Change in unrealized net gain (loss) on securities available-for-sale	142,281							142,281
Non-cash impairment loss on J.C. Penney common shares	0
Amounts reclassified related to sale of available-for-sale securities	(42,404)							(42,404)
Pro rata share of other comprehensive (loss) income of nonconsolidated subsidiaries	(22,814)							(22,814)
Change in value of interest rate swap	18,183							18,183
Adjustments to carry redeemable Class A units at redemption value	(108,252)					(108,252)
Redeemable noncontrolling interests' share of above adjustments	(5,296)							(5,296)
Preferred unit and share redemptions	(1,130)						(1,130)
Deconsolidation of partially owned entity	(165,427)								(165,427)
Consolidation of a partially owned entity	16,799								16,799
Other	(6,830)					2,472	(7,271)	533	(2,564)
Ending balance, Value at Dec. 31, 2013	$ 7,594,744			$ 1,277,225	$ 7,469	$ 7,143,840	$ (1,734,839)	$ 71,537	$ 829,512
Ending balance, Shares at Dec. 31, 2013				52,683	187,285