Business Segments (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Summary information for the reportable segments
Rental and other property revenues	$ 273,384	$ 266,728	$ 545,176	$ 533,332
Asset management and tax credit revenues	7,651	9,796	16,887	14,497
Total revenues	281,035	276,524	562,063	547,829
Property operating expenses	117,379	123,126	240,908	250,266
Investment management expenses	2,187	5,141	5,219	8,370
Depreciation and amortization	94,084	102,809	193,117	206,092
General and administrative expenses	12,372	15,184	23,498	26,919
Other expenses (income), net	5,222	(4,485)	9,156	(2,148)
Total operating expenses	231,244	241,775	471,898	489,499
Net operating income (loss)	49,791	34,749	90,165	58,330
Other items included in continuing operations	(93,231)	(73,015)	(164,016)	(132,288)
Income (loss) from continuing operations	(43,440)	(38,266)	(73,851)	(73,958)
Conventional Real Estate Operations [Member]
Summary information for the reportable segments
Rental and other property revenues	208,253	203,251	414,800	407,082
Total revenues	208,253	203,251	414,800	407,082
Property operating expenses	77,323	78,396	156,752	162,300
Total operating expenses	77,323	78,396	156,752	162,300
Net operating income (loss)	130,930	124,855	258,048	244,782
Income (loss) from continuing operations	130,930	124,855	258,048	244,782
Affordable Real Estate Operations [Member]
Summary information for the reportable segments
Rental and other property revenues	32,826	31,661	65,704	62,723
Total revenues	32,826	31,661	65,704	62,723
Property operating expenses	13,599	13,924	27,346	28,805
Total operating expenses	13,599	13,924	27,346	28,805
Net operating income (loss)	19,227	17,737	38,358	33,918
Income (loss) from continuing operations	19,227	17,737	38,358	33,918
Proportionate Adjustments [Member]
Summary information for the reportable segments
Rental and other property revenues	32,029	31,159	63,816	62,137
Total revenues	32,029	31,159	63,816	62,137
Property operating expenses	13,912	13,978	28,332	29,025
Total operating expenses	13,912	13,978	28,332	29,025
Net operating income (loss)	18,117	17,181	35,484	33,112
Income (loss) from continuing operations	18,117	17,181	35,484	33,112
Corporate and Amounts Not Allocated to Segments [Member]
Summary information for the reportable segments
Rental and other property revenues	276	657	856	1,390
Asset management and tax credit revenues	7,651	9,796	16,887	14,497
Total revenues	7,927	10,453	17,743	15,887
Property operating expenses	12,545	16,828	28,478	30,136
Investment management expenses	2,187	5,141	5,219	8,370
Depreciation and amortization	94,084	102,809	193,117	206,092
General and administrative expenses	12,372	15,184	23,498	26,919
Other expenses (income), net	5,222	(4,485)	9,156	(2,148)
Total operating expenses	126,410	135,477	259,468	269,369
Net operating income (loss)	(118,483)	(125,024)	(241,725)	(253,482)
Other items included in continuing operations	(93,231)	(73,015)	(164,016)	(132,288)
Income (loss) from continuing operations	$ (211,714)	$ (198,039)	$ (405,741)	$ (385,770)