Investments in Partially Owned Entities (Details) (USD $)	3 Months Ended		25 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Apr. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Investments In Partially Owned Entities (Textuals) [Abstract]
Joint Venture Partner Ownership Percentage	80.00%		80.00%
Investments in unconsolidated entities	$ 89,284,000		$ 89,284,000		$ 105,434,000
Equity Method Investment, Ownership Percentage	20.00%		20.00%
Secured Debt	4,957,876,000		4,957,876,000		5,086,515,000
Debt Instrument, Interest Rate, Stated Percentage				6.584%
Debt Instrument, Maturity Date	May 01, 2061
Number of Joint Ventures	2		2
Partners Payments To Acquire Equity Method Investments	40,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	5,968,000		5,968,000	130,300,000
Investment in Joint Venture	339,400,000		339,400,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	122,661,000		122,661,000		124,909,000
Distributions from unconsolidated entities - return of capital	18,969,000	7,680,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	389		389
Number of Units in Real Estate Property	108,793		108,793
ASSETS
Investment in real estate	27,795,858,000		27,795,858,000		27,675,383,000
Real Estate Investment Property, Accumulated Depreciation	(5,600,485,000)		(5,600,485,000)		(5,432,805,000)
Investment in real estate, net	22,195,373,000		22,195,373,000		22,242,578,000
Cash and cash equivalents	49,418,000	37,209,000	49,418,000		40,080,000	53,534,000
Investments in unconsolidated entities	89,284,000		89,284,000		105,434,000
Deposits - restricted	203,800,000		203,800,000		72,303,000
Deferred financing costs, net	55,791,000		55,791,000		58,380,000
Other Assets	384,723,000		384,723,000		383,754,000
Total assets	23,029,048,000		23,029,048,000		22,950,614,000
LIABILITIES AND EQUITY
Secured Debt	4,957,876,000		4,957,876,000		5,086,515,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	202,110,000		202,110,000		153,590,000
Accrued interest payable	84,670,000		84,670,000		89,540,000
Other liabilities	383,057,000		383,057,000		389,915,000
Security deposits	75,294,000		75,294,000		75,633,000
Total liabilities	11,813,593,000		11,813,593,000		11,742,105,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	122,661,000		122,661,000		124,909,000
Total liabilities and equity	23,029,048,000		23,029,048,000		22,950,614,000
Partially Owned Property Income Statement Schedule
Operating revenue	666,371,000	633,442,000
Depreciation	194,521,000	185,167,000
General and administrative/other	19,922,000	17,576,000
Operating Income	218,171,000	199,259,000
Interest and other income	120,000	605,000
Interest:
Expense incurred, net	108,622,000	113,049,000
Amortization of deferred financing costs	(2,589,000)	(2,792,000)
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	107,150,000	83,359,000
Income and other tax (expense) benefit	(43,000)	(240,000)
Income (loss) from investments in unconsolidated entities	2,963,000	(1,409,000)
Net income	190,224,000	82,732,000
Consolidated Development Projects Held for and or Under Development [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	0		0
Secured Debt	0		0
Noncontrolling Interests - Partially Owned Properties/Partners' equity	117,350,000		117,350,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	0		0
Number of Units in Real Estate Property	0		0
ASSETS
Investment in real estate	347,809,000		347,809,000
Real Estate Investment Property, Accumulated Depreciation	(991,000)		(991,000)
Investment in real estate, net	346,818,000		346,818,000
Cash and cash equivalents	0		0
Investments in unconsolidated entities	0		0
Deposits - restricted	15,640,000		15,640,000
Deferred financing costs, net	0		0
Other Assets	6,697,000		6,697,000
Total assets	369,155,000		369,155,000
LIABILITIES AND EQUITY
Secured Debt	0		0
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	8,731,000		8,731,000
Accrued interest payable	0		0
Other liabilities	257,000		257,000
Security deposits	150,000		150,000
Total liabilities	9,138,000		9,138,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	117,350,000		117,350,000
Company equity/General and Limited Partners' Capital	242,667,000		242,667,000
Total equity/capital	360,017,000		360,017,000
Total liabilities and equity	369,155,000		369,155,000
Partially Owned Property Income Statement Schedule
Operating revenue	250,000
Operating expenses	418,000
Net operating (loss) income	(168,000)
Depreciation	991,000
General and administrative/other	0
Operating Income	(1,159,000)
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	(1,159,000)
Income and other tax (expense) benefit	0
Income (loss) from investments in unconsolidated entities	0
Net income	(1,159,000)
Consolidated Operating [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	51,363,000		51,363,000
Secured Debt	360,567,000		360,567,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	5,311,000		5,311,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	19		19
Number of Units in Real Estate Property	3,771		3,771
ASSETS
Investment in real estate	684,686,000		684,686,000
Real Estate Investment Property, Accumulated Depreciation	(200,002,000)		(200,002,000)
Investment in real estate, net	484,684,000		484,684,000
Cash and cash equivalents	13,775,000		13,775,000
Investments in unconsolidated entities	51,363,000		51,363,000
Deposits - restricted	310,000		310,000
Deferred financing costs, net	2,052,000		2,052,000
Other Assets	26,227,000		26,227,000
Total assets	578,411,000		578,411,000
LIABILITIES AND EQUITY
Secured Debt	360,567,000		360,567,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	3,188,000		3,188,000
Accrued interest payable	1,283,000		1,283,000
Other liabilities	576,000		576,000
Security deposits	1,976,000		1,976,000
Total liabilities	367,590,000		367,590,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	5,311,000		5,311,000
Company equity/General and Limited Partners' Capital	205,510,000		205,510,000
Total equity/capital	210,821,000		210,821,000
Total liabilities and equity	578,411,000		578,411,000
Partially Owned Property Income Statement Schedule
Operating revenue	22,688,000
Operating expenses	6,875,000
Net operating (loss) income	15,813,000
Depreciation	5,520,000
General and administrative/other	15,000
Operating Income	10,278,000
Interest and other income	4,000
Other expenses	(50,000)
Interest:
Expense incurred, net	(3,884,000)
Amortization of deferred financing costs	(89,000)
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	6,259,000
Income and other tax (expense) benefit	(35,000)
Income (loss) from investments in unconsolidated entities	(377,000)
Net income	5,847,000
Consolidated Total [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	51,363,000		51,363,000
Secured Debt	360,567,000		360,567,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	122,661,000		122,661,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	19		19
Number of Units in Real Estate Property	3,771		3,771
ASSETS
Investment in real estate	1,032,495,000		1,032,495,000
Real Estate Investment Property, Accumulated Depreciation	(200,993,000)		(200,993,000)
Investment in real estate, net	831,502,000		831,502,000
Cash and cash equivalents	13,775,000		13,775,000
Investments in unconsolidated entities	51,363,000		51,363,000
Deposits - restricted	15,950,000		15,950,000
Deferred financing costs, net	2,052,000		2,052,000
Other Assets	32,924,000		32,924,000
Total assets	947,566,000		947,566,000
LIABILITIES AND EQUITY
Secured Debt	360,567,000		360,567,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	11,919,000		11,919,000
Accrued interest payable	1,283,000		1,283,000
Other liabilities	833,000		833,000
Security deposits	2,126,000		2,126,000
Total liabilities	376,728,000		376,728,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	122,661,000		122,661,000
Company equity/General and Limited Partners' Capital	448,177,000		448,177,000
Total equity/capital	570,838,000		570,838,000
Total liabilities and equity	947,566,000		947,566,000
Partially Owned Property Income Statement Schedule
Operating revenue	22,938,000
Operating expenses	7,293,000
Net operating (loss) income	15,645,000
Depreciation	6,511,000
General and administrative/other	15,000
Operating Income	9,119,000
Interest and other income	4,000
Other expenses	(50,000)
Interest:
Expense incurred, net	(3,884,000)
Amortization of deferred financing costs	(89,000)
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	5,100,000
Income and other tax (expense) benefit	(35,000)
Income (loss) from investments in unconsolidated entities	(377,000)
Net income	4,688,000
Unconsolidated Operating [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	0		0
Secured Debt	175,276,000		175,276,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	90,878,000		90,878,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	3		3
Number of Units in Real Estate Property	1,281		1,281
ASSETS
Investment in real estate	290,077,000		290,077,000
Real Estate Investment Property, Accumulated Depreciation	(21,388,000)		(21,388,000)
Investment in real estate, net	268,689,000		268,689,000
Cash and cash equivalents	7,598,000		7,598,000
Investments in unconsolidated entities	0		0
Deposits - restricted	246,000		246,000
Deferred financing costs, net	7,000		7,000
Other Assets	1,327,000		1,327,000
Total assets	277,867,000		277,867,000
LIABILITIES AND EQUITY
Secured Debt	175,276,000		175,276,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	389,000		389,000
Accrued interest payable	691,000		691,000
Other liabilities	834,000		834,000
Security deposits	531,000		531,000
Total liabilities	177,721,000		177,721,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	90,878,000		90,878,000
Company equity/General and Limited Partners' Capital	9,268,000		9,268,000
Total equity/capital	100,146,000		100,146,000
Total liabilities and equity	277,867,000		277,867,000
Partially Owned Property Income Statement Schedule
Operating revenue	7,813,000
Operating expenses	2,443,000
Net operating (loss) income	5,370,000
Depreciation	3,076,000
General and administrative/other	56,000
Operating Income	2,238,000
Interest and other income	0
Other expenses	0
Interest:
Expense incurred, net	(2,346,000)
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	(109,000)
Income and other tax (expense) benefit	(18,000)
Income (loss) from investments in unconsolidated entities	0
Net income	(127,000)
Unconsolidated Total [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Investments in unconsolidated entities	0		0
Secured Debt	175,276,000		175,276,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	90,878,000		90,878,000
Partially Owned Property Balance Sheet Schedule
Number of Real Estate Properties	3		3
Number of Units in Real Estate Property	1,281		1,281
ASSETS
Investment in real estate	290,077,000		290,077,000
Real Estate Investment Property, Accumulated Depreciation	(21,388,000)		(21,388,000)
Investment in real estate, net	268,689,000		268,689,000
Cash and cash equivalents	7,598,000		7,598,000
Investments in unconsolidated entities	0		0
Deposits - restricted	246,000		246,000
Deferred financing costs, net	7,000		7,000
Other Assets	1,327,000		1,327,000
Total assets	277,867,000		277,867,000
LIABILITIES AND EQUITY
Secured Debt	175,276,000		175,276,000
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable	389,000		389,000
Accrued interest payable	691,000		691,000
Other liabilities	834,000		834,000
Security deposits	531,000		531,000
Total liabilities	177,721,000		177,721,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	90,878,000		90,878,000
Company equity/General and Limited Partners' Capital	9,268,000		9,268,000
Total equity/capital	100,146,000		100,146,000
Total liabilities and equity	277,867,000		277,867,000
Partially Owned Property Income Statement Schedule
Operating revenue	7,813,000
Operating expenses	2,443,000
Net operating (loss) income	5,370,000
Depreciation	3,076,000
General and administrative/other	56,000
Operating Income	2,238,000
Interest and other income	0
Other expenses	0
Interest:
Expense incurred, net	(2,346,000)
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	(109,000)
Income and other tax (expense) benefit	(18,000)
Income (loss) from investments in unconsolidated entities	0
Net income	(127,000)
Archstone Transaction [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Liquidation Value Preferred Interests	72,600,000		72,600,000
Germany [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Distributions from unconsolidated entities - return of capital	2,000,000		100,500,000
Residual JV [Domain]
Investments In Partially Owned Entities (Textuals) [Abstract]
Business Acquisition, Percentage of Voting Interests Acquired	60.00%		60.00%
Joint Venture Partner Ownership Percentage	40.00%		40.00%
Investments in unconsolidated entities	147,600,000		147,600,000
Distributions from unconsolidated entities - return of capital	19,000,000
ASSETS
Investments in unconsolidated entities	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	10,400,000
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%
Initial Basis of Real Estate, Consolidated	198,500,000		198,500,000
Investments in unconsolidated entities	56,500,000		56,500,000
Partially Owned Property Balance Sheet Schedule
Number of Units in Real Estate Property	432		432
ASSETS
Investments in unconsolidated entities	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%
Initial Basis of Real Estate, Unconsolidated	5,100,000		5,100,000
Secured Debt	29,800,000		29,800,000
Debt Instrument, Interest Rate, Stated Percentage	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
LIABILITIES AND EQUITY
Secured Debt	29,800,000		29,800,000
Joint Venture Partner [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Land purchase price	57,900,000		57,900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	75,700,000		75,700,000
Noncontrolling Interests - Partially Owned Properties/Partners' equity	117,400,000		117,400,000
LIABILITIES AND EQUITY
Noncontrolling Interests - Partially Owned Properties/Partners' equity	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
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	102,500,000		102,500,000
Nexus Sawgrass [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Secured Debt	48,600,000		48,600,000
Debt Instrument, Interest Rate, Stated Percentage	5.60%		5.60%
Debt Instrument, Maturity Date	Jan. 01, 2021
Project Cost	78,600,000		78,600,000
Maximum Debt Commitment	48,700,000		48,700,000
LIABILITIES AND EQUITY
Secured Debt	48,600,000		48,600,000
Domain [Member]
Investments In Partially Owned Entities (Textuals) [Abstract]
Secured Debt	96,800,000		96,800,000
Debt Instrument, Interest Rate, Stated Percentage	5.75%		5.75%
Debt Instrument, Maturity Date	Jan. 01, 2022
Project Cost	155,800,000		155,800,000
Maximum Debt Commitment	98,600,000		98,600,000
LIABILITIES AND EQUITY
Secured Debt	$ 96,800,000		$ 96,800,000