Investments in Partially Owned Entities (Details) - USD ($)	3 Months Ended		6 Months Ended		28 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Investments In Partially Owned Entities (Textuals) [Abstract]
Joint Venture Partner Ownership Percentage	80.00%		80.00%		80.00%
Investments in unconsolidated entities	$ 94,718,000		$ 94,718,000		$ 94,718,000	$ 105,434,000
Equity Method Investment, Ownership Percentage	20.00%		20.00%		20.00%
Secured Debt	$ 4,952,579,000		$ 4,952,579,000		$ 4,952,579,000	5,086,515,000
Debt Instrument, Maturity Date			May 01, 2061
Number of Joint Ventures	2		2		2
Partners Payments To Acquire Equity Method Investments			$ 40,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 136,243,000		136,243,000		$ 136,243,000
Investment in Joint Venture	342,200,000		342,200,000		342,200,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	$ 122,368,000		122,368,000		$ 122,368,000	124,909,000
Distributions from unconsolidated entities - return of capital			$ 26,147,000	$ 64,669,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	388		388		388
Number of Units in Real Estate Property	108,430		108,430		108,430
ASSETS
Investment in real estate	$ 28,032,906,000		$ 28,032,906,000		$ 28,032,906,000	27,675,383,000
Real Estate Investment Property, Accumulated Depreciation	(5,736,913,000)		(5,736,913,000)		(5,736,913,000)	(5,432,805,000)
Investment in real estate, net	22,295,993,000		22,295,993,000		22,295,993,000	22,242,578,000
Cash and cash equivalents	92,109,000	$ 76,132,000	92,109,000	76,132,000	92,109,000	40,080,000	$ 53,534,000
Investments in unconsolidated entities	94,718,000		94,718,000		94,718,000	105,434,000
Deposits - restricted	103,508,000		103,508,000		103,508,000	72,303,000
Deferred financing costs, net	59,605,000		59,605,000		59,605,000	58,380,000
Other Assets	383,035,000		383,035,000		383,035,000	383,754,000
Total assets	23,081,830,000		23,081,830,000		23,081,830,000	22,950,614,000
LIABILITIES AND EQUITY
Secured Debt	4,952,579,000		4,952,579,000		4,952,579,000	5,086,515,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	193,096,000		193,096,000		193,096,000	153,590,000
Accrued interest payable	87,131,000		87,131,000		87,131,000	89,540,000
Other liabilities	355,632,000		355,632,000		355,632,000	389,915,000
Security deposits	76,112,000		76,112,000		76,112,000	75,633,000
Total liabilities	11,748,919,000		11,748,919,000		11,748,919,000	11,742,105,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	122,368,000		122,368,000		122,368,000	124,909,000
Total liabilities and equity	23,081,830,000		23,081,830,000		23,081,830,000	$ 22,950,614,000
Partially Owned Property Income Statement Schedule
Operating revenue	679,112,000	652,568,000	1,345,483,000	1,286,010,000
Depreciation	194,282,000	190,136,000	388,803,000	375,303,000
General and administrative/other	15,730,000	13,752,000	35,652,000	31,328,000
Operating Income	246,184,000	228,310,000	464,355,000	427,569,000
Interest and other income	6,481,000	2,032,000	6,650,000	2,637,000
Interest:
Expense incurred, net	110,795,000	115,924,000	219,417,000	228,973,000
Amortization of deferred financing costs	(2,538,000)	(3,134,000)	(5,127,000)	(5,926,000)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations	137,562,000	109,745,000	244,761,000	193,104,000
Income and other tax (expense) benefit	(326,000)	(646,000)	(369,000)	(886,000)
Income (loss) from investments in unconsolidated entities	12,466,000	(7,616,000)	15,429,000	(9,025,000)
Net income	298,618,000	$ 117,720,000	488,842,000	$ 200,452,000
Consolidated Development Projects Held for and or Under Development [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	0		0		0
Secured Debt	0		0		0
Noncontrolling Interests - Partially Owned Properties/Partners' equity	$ 117,350,000		$ 117,350,000		$ 117,350,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	0		0		0
Number of Units in Real Estate Property	0		0		0
ASSETS
Investment in real estate	$ 351,977,000		$ 351,977,000		$ 351,977,000
Real Estate Investment Property, Accumulated Depreciation	(2,339,000)		(2,339,000)		(2,339,000)
Investment in real estate, net	349,638,000		349,638,000		349,638,000
Cash and cash equivalents	0		0		0
Investments in unconsolidated entities	0		0		0
Deposits - restricted	11,609,000		11,609,000		11,609,000
Deferred financing costs, net	0		0		0
Other Assets	6,988,000		6,988,000		6,988,000
Total assets	368,235,000		368,235,000		368,235,000
LIABILITIES AND EQUITY
Secured Debt	0		0		0
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	5,756,000		5,756,000		5,756,000
Accrued interest payable	0		0		0
Other liabilities	615,000		615,000		615,000
Security deposits	589,000		589,000		589,000
Total liabilities	6,960,000		6,960,000		6,960,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	117,350,000		117,350,000		117,350,000
Company equity/General and Limited Partners' Capital	243,925,000		243,925,000		243,925,000
Total equity/capital	361,275,000		361,275,000		361,275,000
Total liabilities and equity	368,235,000		368,235,000		368,235,000
Partially Owned Property Income Statement Schedule
Operating revenue			1,103,000
Operating expenses			851,000
Net operating (loss) income			252,000
Depreciation			2,339,000
General and administrative/other			1,000
Operating Income			(2,088,000)
Interest and other income			0
Other expenses			0
Interest:
Expense incurred, net			0
Amortization of deferred financing costs			0
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations			(2,088,000)
Income and other tax (expense) benefit			0
Income (loss) from investments in unconsolidated entities			0
Net income			(2,088,000)
Consolidated Operating [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	50,771,000		50,771,000		50,771,000
Secured Debt	360,654,000		360,654,000		360,654,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	$ 5,018,000		$ 5,018,000		$ 5,018,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	19		19		19
Number of Units in Real Estate Property	3,771		3,771		3,771
ASSETS
Investment in real estate	$ 686,120,000		$ 686,120,000		$ 686,120,000
Real Estate Investment Property, Accumulated Depreciation	(205,554,000)		(205,554,000)		(205,554,000)
Investment in real estate, net	480,566,000		480,566,000		480,566,000
Cash and cash equivalents	17,482,000		17,482,000		17,482,000
Investments in unconsolidated entities	50,771,000		50,771,000		50,771,000
Deposits - restricted	345,000		345,000		345,000
Deferred financing costs, net	1,963,000		1,963,000		1,963,000
Other Assets	25,959,000		25,959,000		25,959,000
Total assets	577,086,000		577,086,000		577,086,000
LIABILITIES AND EQUITY
Secured Debt	360,654,000		360,654,000		360,654,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	1,939,000		1,939,000		1,939,000
Accrued interest payable	1,266,000		1,266,000		1,266,000
Other liabilities	819,000		819,000		819,000
Security deposits	2,002,000		2,002,000		2,002,000
Total liabilities	366,680,000		366,680,000		366,680,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	5,018,000		5,018,000		5,018,000
Company equity/General and Limited Partners' Capital	205,388,000		205,388,000		205,388,000
Total equity/capital	210,406,000		210,406,000		210,406,000
Total liabilities and equity	577,086,000		577,086,000		577,086,000
Partially Owned Property Income Statement Schedule
Operating revenue			46,071,000
Operating expenses			13,545,000
Net operating (loss) income			32,526,000
Depreciation			11,073,000
General and administrative/other			41,000
Operating Income			21,412,000
Interest and other income			5,000
Other expenses			(50,000)
Interest:
Expense incurred, net			(7,786,000)
Amortization of deferred financing costs			(177,000)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations			13,404,000
Income and other tax (expense) benefit			(35,000)
Income (loss) from investments in unconsolidated entities			(739,000)
Net income			12,630,000
Consolidated Total [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	50,771,000		50,771,000		50,771,000
Secured Debt	360,654,000		360,654,000		360,654,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	$ 122,368,000		$ 122,368,000		$ 122,368,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	19		19		19
Number of Units in Real Estate Property	3,771		3,771		3,771
ASSETS
Investment in real estate	$ 1,038,097,000		$ 1,038,097,000		$ 1,038,097,000
Real Estate Investment Property, Accumulated Depreciation	(207,893,000)		(207,893,000)		(207,893,000)
Investment in real estate, net	830,204,000		830,204,000		830,204,000
Cash and cash equivalents	17,482,000		17,482,000		17,482,000
Investments in unconsolidated entities	50,771,000		50,771,000		50,771,000
Deposits - restricted	11,954,000		11,954,000		11,954,000
Deferred financing costs, net	1,963,000		1,963,000		1,963,000
Other Assets	32,947,000		32,947,000		32,947,000
Total assets	945,321,000		945,321,000		945,321,000
LIABILITIES AND EQUITY
Secured Debt	360,654,000		360,654,000		360,654,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	7,695,000		7,695,000		7,695,000
Accrued interest payable	1,266,000		1,266,000		1,266,000
Other liabilities	1,434,000		1,434,000		1,434,000
Security deposits	2,591,000		2,591,000		2,591,000
Total liabilities	373,640,000		373,640,000		373,640,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	122,368,000		122,368,000		122,368,000
Company equity/General and Limited Partners' Capital	449,313,000		449,313,000		449,313,000
Total equity/capital	571,681,000		571,681,000		571,681,000
Total liabilities and equity	945,321,000		945,321,000		945,321,000
Partially Owned Property Income Statement Schedule
Operating revenue			47,174,000
Operating expenses			14,396,000
Net operating (loss) income			32,778,000
Depreciation			13,412,000
General and administrative/other			42,000
Operating Income			19,324,000
Interest and other income			5,000
Other expenses			(50,000)
Interest:
Expense incurred, net			(7,786,000)
Amortization of deferred financing costs			(177,000)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations			11,316,000
Income and other tax (expense) benefit			(35,000)
Income (loss) from investments in unconsolidated entities			(739,000)
Net income			10,542,000
Unconsolidated Operating [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	0		0		0
Secured Debt	175,135,000		175,135,000		175,135,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	$ 90,878,000		$ 90,878,000		$ 90,878,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	3		3		3
Number of Units in Real Estate Property	1,281		1,281		1,281
ASSETS
Investment in real estate	$ 290,442,000		$ 290,442,000		$ 290,442,000
Real Estate Investment Property, Accumulated Depreciation	(24,471,000)		(24,471,000)		(24,471,000)
Investment in real estate, net	265,971,000		265,971,000		265,971,000
Cash and cash equivalents	8,793,000		8,793,000		8,793,000
Investments in unconsolidated entities	0		0		0
Deposits - restricted	273,000		273,000		273,000
Deferred financing costs, net	7,000		7,000		7,000
Other Assets	703,000		703,000		703,000
Total assets	275,747,000		275,747,000		275,747,000
LIABILITIES AND EQUITY
Secured Debt	175,135,000		175,135,000		175,135,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	1,486,000		1,486,000		1,486,000
Accrued interest payable	691,000		691,000		691,000
Other liabilities	325,000		325,000		325,000
Security deposits	592,000		592,000		592,000
Total liabilities	178,229,000		178,229,000		178,229,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	90,878,000		90,878,000		90,878,000
Company equity/General and Limited Partners' Capital	6,640,000		6,640,000		6,640,000
Total equity/capital	97,518,000		97,518,000		97,518,000
Total liabilities and equity	275,747,000		275,747,000		275,747,000
Partially Owned Property Income Statement Schedule
Operating revenue			15,918,000
Operating expenses			5,388,000
Net operating (loss) income			10,530,000
Depreciation			6,159,000
General and administrative/other			119,000
Operating Income			4,252,000
Interest and other income			0
Other expenses			0
Interest:
Expense incurred, net			(4,697,000)
Amortization of deferred financing costs			(1,000)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations			(446,000)
Income and other tax (expense) benefit			(18,000)
Income (loss) from investments in unconsolidated entities			0
Net income			(464,000)
Unconsolidated Total [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	0		0		0
Secured Debt	175,135,000		175,135,000		175,135,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	$ 90,878,000		$ 90,878,000		$ 90,878,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	3		3		3
Number of Units in Real Estate Property	1,281		1,281		1,281
ASSETS
Investment in real estate	$ 290,442,000		$ 290,442,000		$ 290,442,000
Real Estate Investment Property, Accumulated Depreciation	(24,471,000)		(24,471,000)		(24,471,000)
Investment in real estate, net	265,971,000		265,971,000		265,971,000
Cash and cash equivalents	8,793,000		8,793,000		8,793,000
Investments in unconsolidated entities	0		0		0
Deposits - restricted	273,000		273,000		273,000
Deferred financing costs, net	7,000		7,000		7,000
Other Assets	703,000		703,000		703,000
Total assets	275,747,000		275,747,000		275,747,000
LIABILITIES AND EQUITY
Secured Debt	175,135,000		175,135,000		175,135,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	1,486,000		1,486,000		1,486,000
Accrued interest payable	691,000		691,000		691,000
Other liabilities	325,000		325,000		325,000
Security deposits	592,000		592,000		592,000
Total liabilities	178,229,000		178,229,000		178,229,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	90,878,000		90,878,000		90,878,000
Company equity/General and Limited Partners' Capital	6,640,000		6,640,000		6,640,000
Total equity/capital	97,518,000		97,518,000		97,518,000
Total liabilities and equity	275,747,000		275,747,000		275,747,000
Partially Owned Property Income Statement Schedule
Operating revenue			15,918,000
Operating expenses			5,388,000
Net operating (loss) income			10,530,000
Depreciation			6,159,000
General and administrative/other			119,000
Operating Income			4,252,000
Interest and other income			0
Other expenses			0
Interest:
Expense incurred, net			(4,697,000)
Amortization of deferred financing costs			(1,000)
Income before income and other taxes, income (loss) from investments in unconsolidated entities, net gain (loss) on sales of real estate properties and land parcels and discontinued operations			(446,000)
Income and other tax (expense) benefit			(18,000)
Income (loss) from investments in unconsolidated entities			0
Net income			(464,000)
Archstone Transaction [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Liquidation Value Preferred Interests	$ 71,200,000		71,200,000		71,200,000
Germany [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Distributions from unconsolidated entities - return of capital			$ 2,300,000		$ 100,800,000
Residual JV [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Business Acquisition, Percentage of Voting Interests Acquired	60.00%		60.00%		60.00%
Joint Venture Partner Ownership Percentage	40.00%		40.00%		40.00%
Investments in unconsolidated entities	$ 147,600,000		$ 147,600,000		$ 147,600,000
Distributions from unconsolidated entities - return of capital			26,100,000
ASSETS
Investments in unconsolidated entities	$ 147,600,000		147,600,000		$ 147,600,000
Residual JV [Domain] | Rental Properties Disposed of [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Distributions from unconsolidated entities - return of capital			17,200,000
Residual JV [Domain] | Settled Litigation [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Distributions from unconsolidated entities - return of capital			$ 6,600,000
Wisconsin Place [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Business Acquisition, Percentage of Voting Interests Acquired	75.00%		75.00%		75.00%
Initial Basis of Real Estate, Consolidated	$ 198,500,000		$ 198,500,000		$ 198,500,000
Investments in unconsolidated entities	$ 56,500,000		$ 56,500,000		$ 56,500,000
Partially Owned Property Balance Sheet Schedule
Number of Units in Real Estate Property	432		432		432
ASSETS
Investments in unconsolidated entities	$ 56,500,000		$ 56,500,000		$ 56,500,000
Waterton Tenside [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Equity Method Investment, Ownership Percentage	20.00%		20.00%		20.00%
Initial Basis of Real Estate, Unconsolidated	$ 5,100,000		$ 5,100,000		$ 5,100,000
Secured Debt	$ 29,700,000		$ 29,700,000		$ 29,700,000
Debt Instrument, Interest Rate, Stated Percentage	3.66%		3.66%		3.66%
Debt Instrument, Maturity Date			Dec. 01, 2018
Partially Owned Property Balance Sheet Schedule
Number of Units in Real Estate Property	336		336		336
LIABILITIES AND EQUITY
Secured Debt	$ 29,700,000		$ 29,700,000		$ 29,700,000
Joint Venture Partner [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Land purchase price	57,900,000		57,900,000		57,900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	75,700,000		75,700,000		75,700,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	117,400,000		117,400,000		117,400,000
LIABILITIES AND EQUITY
Noncontrolling Interests - Partially Owned Properties/Partners' equity	117,400,000		117,400,000		117,400,000
Company's Portion [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Land purchase price	76,100,000		76,100,000		76,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	102,500,000		102,500,000		102,500,000
Nexus Sawgrass [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Secured Debt	$ 48,600,000		$ 48,600,000		$ 48,600,000
Debt Instrument, Interest Rate, Stated Percentage	5.60%		5.60%		5.60%
Debt Instrument, Maturity Date			Jan. 01, 2021
Project Cost	$ 78,600,000		$ 78,600,000		$ 78,600,000
LIABILITIES AND EQUITY
Secured Debt	48,600,000		48,600,000		48,600,000
Domain [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Secured Debt	$ 96,800,000		$ 96,800,000		$ 96,800,000
Debt Instrument, Interest Rate, Stated Percentage	5.75%		5.75%		5.75%
Debt Instrument, Maturity Date			Jan. 01, 2022
Project Cost	$ 155,800,000		$ 155,800,000		$ 155,800,000
LIABILITIES AND EQUITY
Secured Debt	$ 96,800,000		$ 96,800,000		$ 96,800,000