Fair Value Measurements (Assets Measured On Nonrecurring Basis) (Details) (USD $)	1 Months Ended	9 Months Ended			12 Months Ended		1 Months Ended	12 Months Ended				9 Months Ended		12 Months Ended		9 Months Ended		12 Months Ended		9 Months Ended		12 Months Ended																		12 Months Ended						12 Months Ended								12 Months Ended
	Apr. 30, 2011	Sep. 30, 2012		Sep. 30, 2011	Dec. 31, 2011		Apr. 30, 2011 Subordinate Tax Increment Revenue Bonds [Member]	Dec. 31, 2011 Subordinate Tax Increment Revenue Bonds [Member]		Dec. 31, 2010 Subordinate Tax Increment Revenue Bonds [Member]	Apr. 30, 2011 Senior Tax Increment Revenue Bonds [Member]	Sep. 30, 2012 Impaired Property [Member]		Dec. 31, 2011 Impaired Property [Member]		Sep. 30, 2012 Impaired Property Held For Sale [Member]		Dec. 31, 2011 Impaired Property Held For Sale [Member]		Sep. 30, 2012 Impaired Investment In Real Estate Joint Ventures And Partnerships [Member]		Dec. 31, 2011 Impaired Investment In Real Estate Joint Ventures And Partnerships [Member]		Sep. 30, 2012 Quoted Prices In Active Markets For Identical Assets And Liabilities (Level1) [Member]	Dec. 31, 2011 Quoted Prices In Active Markets For Identical Assets And Liabilities (Level1) [Member]	Sep. 30, 2012 Significant Other Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) [Member]	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) [Member] Impaired Property [Member]		Sep. 30, 2012 Significant Other Observable Inputs (Level 2) [Member] Impaired Property Held For Sale [Member]		Dec. 31, 2011 Significant Other Observable Inputs (Level 2) [Member] Impaired Property Held For Sale [Member]		Sep. 30, 2012 Significant Other Observable Inputs (Level 2) [Member] Impaired Investment In Real Estate Joint Ventures And Partnerships [Member]		Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member] Subordinate Tax Increment Revenue Bonds [Member]		Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member] Subordinate Tax Increment Revenue Bonds [Member] Minimum [Member]	Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member] Subordinate Tax Increment Revenue Bonds [Member] Maximum [Member]	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Impaired Property [Member]		Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member] Impaired Property [Member]		Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member] Impaired Property [Member] Minimum [Member]	Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member] Impaired Property [Member] Maximum [Member]	Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member] Impaired Property Held For Sale [Member]		Sep. 30, 2012 Significant Unobservable Inputs (Level 3) [Member] Impaired Property Held For Sale [Member]		Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member] Impaired Investment In Real Estate Joint Ventures And Partnerships [Member]		Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member] Impaired Investment In Real Estate Joint Ventures And Partnerships [Member] Minimum [Member]	Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member] Impaired Investment In Real Estate Joint Ventures And Partnerships [Member] Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property												$ 13,906,000	[1]	$ 98,596,000	[2]													$ 389,000	[2]													$ 13,906,000	[1]	$ 98,207,000	[2]
Property held for sale																49,806,000	[3]	45,157,000	[4]											39,131,000	[3]	43,657,000	[4]															1,500,000	[4]	10,675,000	[3]
Investment in real estate joint ventures and partnerships																				24,231,000	[5]	6,311,000	[6]											24,231,000	[5]																	6,311,000	[6]
Investments								26,723,000	[7]																											26,505,000	26,505,000	26,723,000	[7]
Total		87,943,000			176,787,000																			0	0	63,362,000	44,046,000									24,581,000	132,741,000
Total Gains (Losses)		(14,306,000)	[8]		(71,195,000)	[9]		(18,737,000)	[7],[9]	(11,700,000)		(2,897,000)	[1],[8]	(36,907,000)	[2],[9]	(4,801,000)	[3],[8]	(13,799,000)	[4],[9]	(6,608,000)	[5],[8]	(1,752,000)	[6],[9]
Property, net		3,452,138,000	[10]		3,702,236,000	[10]						16,800,000		135,500,000
Property held for sale, net		73,404,000			73,241,000											53,800,000		57,000,000
Cost to sell property																800,000		2,000,000
Assumption For Fair Value Discount Rate																																														8.00%	13.00%	10.00%
Investment in real estate joint ventures and partnerships, net		300,471,000			341,608,000															30,800,000		8,100,000
Assumption For Fair Value Market Capitalization Rate																																																						7.00%	9.00%
Cash received on exchange of bonds	16,500,000	0		16,545,000
Receipt Of Investments							57,700,000
Investment at fair value							10,700,000				51,300,000
Investment Owned, at Cost							$ 22,400,000
Assumption For Fair Value Expected Future Growth Rate																																								1.00%	4.00%
Assumption For Fair Value Expected Inflation Rate																																								1.00%	2.00%

[1] In accordance with our policy of evaluating and recording impairments on the disposal of long-lived assets, property with a carrying amount of $16.8 million was written down to a fair value of $13.9 million, resulting in a loss of $2.9 million, which was included in earnings for the nine month period. Management’s estimate of the fair value of these properties was determined using Level 3 inputs. See the quantitative information about the significant unobservable inputs used for our Level 3 fair value measurements table below.

[2] In accordance with our policy of evaluating and recording impairments on the disposal of long-lived assets, property with a carrying amount of $135.5 million was written down to a fair value of $98.6 million, resulting in a loss of $36.9 million, which was included in earnings for the twelve month period. Management’s estimate of the fair value of these properties was determined using the expected sales price of an executed agreement for the Level 2 input and using third party broker valuations, bona fide purchase offers, cash flow models and discount rates ranging from 8% to 13% for the Level 3 inputs.

[3] Property held for sale with a carrying amount of $53.8 million was written down to a fair value of $49.8 million less costs to sell of $0.8 million, resulting in a loss of $4.8 million, which was included in discontinued operations in the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) for the nine month period. Management’s estimate of the fair value of these properties was determined using bona fide purchase offers for the Level 2 inputs, and see the quantitative information about the significant unobservable inputs used for our Level 3 fair value measurements table below.

[4] Property held for sale with a carrying amount of $57.0 million was written down to a fair value of $45.2 million less costs to sell of $2.0 million, resulting in a loss of $13.8 million, which was included in discontinued operations in the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) for the twelve month period. Management’s estimate of the fair value of these properties was determined using the expected sales price of executed agreements for the Level 2 inputs and a cash flow model using a discount rate of 10% for the Level 3 input.

[5] Our net investment in real estate joint ventures and partnerships with a carrying amount of $30.8 million was written down to a fair value of $24.2 million, resulting in a loss of $6.6 million, which was included in earnings for the nine month period. Management’s estimate of the fair value of this investment was determined using the weighted average of the bona fide purchase offers received for the Level 2 inputs.

[6] Our net investment in real estate joint ventures and partnerships with a carrying amount of $8.1 million was written down to a fair value of $6.3 million, resulting in a loss of $1.8 million, which was included in earnings for the twelve month period. Management’s estimate of the fair value of these investments was determined using the life and other terms of the investment, our partner’s financial condition, cash flow models and capitalization rates ranging from 7% to 9% for the Level 3 inputs.

[7] A net credit loss on the exchange of bonds of $18.7 million was recognized upon the recall and replacement of our investment in tax increment revenue bonds by the Agency in April 2011. The exchange transaction resulted in us receiving approximately $16.5 million in cash proceeds and $57.7 million in new subordinated bonds replacing the face value of our $51.3 million of senior bonds and $22.4 million of subordinate bonds, which had been previously written down to a fair value of $10.7 million. The carrying value of the $57.7 million subordinated bonds received in the exchange were written down to their fair value of $26.7 million, of which a loss of $11.7 million was previously recognized in December 2010. The net credit loss resulted as management did not expect to recover the par value of the bonds based upon changes in terms of the bonds and future sales tax revenue projections of the development project through their maturity. Management’s estimates of the fair value of these investments were determined using third-party sales revenue projections, future growth rates ranging from 1% to 4% and inflation rates ranging from 1% to 2% for the Level 3 inputs.

[8] Total gains (losses) exclude impairments on disposed assets because they are no longer held by us.

[9] Total gains (losses) are reflected throughout 2011 and exclude impairments on disposed assets because they are no longer held by us.

[10] * Consolidated Variable Interest Entities’ Assets and Liabilities included in the above balances (See Note 17):