Business Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Summary information for the reportable segments
Rental and other property revenues (3)	$ 240,136		$ 230,252
Tax credit and asset management revenues	8,788		7,252
Total revenues	248,924		237,504
Property operating expenses (3)	99,270		93,868
Investment management expenses	1,252		1,433
Depreciation and amortization (3)	70,307		75,716
General and administrative expenses	10,532		11,779
Other expense, net	2,390		2,069
Total operating expenses	183,751		184,865
Net operating income (loss)	65,173		52,639
Other items included in continuing operations	(53,133)		(54,302)
Income (loss) from continuing operations	12,040		(1,663)
Conventional Real Estate Operations [Member]
Summary information for the reportable segments
Rental and other property revenues (3)	204,314	[1]	193,441	[1]
Tax credit and asset management revenues
Total revenues	204,314		193,441
Property operating expenses (3)	73,751	[1]	70,099	[1]
Investment management expenses
Depreciation and amortization (3)		[1]		[1]
General and administrative expenses
Other expense, net
Total operating expenses	73,751		70,099
Net operating income (loss)	130,563		123,342
Other items included in continuing operations
Income (loss) from continuing operations	130,563		123,342
Affordable Real Estate Operations [Member]
Summary information for the reportable segments
Rental and other property revenues (3)	24,243	[1]	23,994	[1]
Tax credit and asset management revenues
Total revenues	24,243		23,994
Property operating expenses (3)	10,576	[1]	9,952	[1]
Investment management expenses
Depreciation and amortization (3)		[1]		[1]
General and administrative expenses
Other expense, net
Total operating expenses	10,576		9,952
Net operating income (loss)	13,667		14,042
Other items included in continuing operations
Income (loss) from continuing operations	13,667		14,042
Proportionate Adjustments [Member]
Summary information for the reportable segments
Rental and other property revenues (3)	8,865	[1],[2]	8,476	[1],[2]
Tax credit and asset management revenues		[2]		[2]
Total revenues	8,865	[2]	8,476	[2]
Property operating expenses (3)	3,242	[1],[2]	3,020	[1],[2]
Investment management expenses		[2]		[2]
Depreciation and amortization (3)		[1],[2]		[1],[2]
General and administrative expenses		[2]		[2]
Other expense, net		[2]		[2]
Total operating expenses	3,242	[2]	3,020	[2]
Net operating income (loss)	5,623	[2]	5,456	[2]
Other items included in continuing operations		[2]		[2]
Income (loss) from continuing operations	5,623	[2]	5,456	[2]
Corporate and Amounts Not Allocated to Segments [Member]
Summary information for the reportable segments
Rental and other property revenues (3)	2,714	[3]	4,341	[3]
Tax credit and asset management revenues	8,788		7,252
Total revenues	11,502	[3]	11,593	[3]
Property operating expenses (3)	11,701	[3]	10,797	[3]
Investment management expenses	1,252		1,433
Depreciation and amortization (3)	70,307		75,716
General and administrative expenses	10,532		11,779
Other expense, net	2,390		2,069
Total operating expenses	96,182	[3]	101,794	[3]
Net operating income (loss)	(84,680)	[3]	(90,201)	[3]
Other items included in continuing operations	(53,133)	[3]	(54,302)	[3]
Income (loss) from continuing operations	$ (137,813)	[3]	$ (144,503)	[3]

[1] Proportionate property net operating income, our key measurement of segment profit or loss excludes property management revenues (which are included in rental and other property revenues), property management expenses and casualty gains and losses (which are included in property operating expenses) and depreciation and amortization and provision for real estate impairment losses. Accordingly, we do not allocate these amounts to our segments.

[2] Represents adjustments for the noncontrolling interests in consolidated real estate partnerships’ share of the results of our consolidated properties and the results of consolidated properties that we do not manage, which are excluded from our measurement of segment performance but included in the related consolidated amounts, and our share of the results of operations of our unconsolidated real estate partnerships that we manage, which are included in our measurement of segment performance but excluded from the related consolidated amounts.

[3] Our basis for assessing segment performance excludes the results of apartment communities sold or classified as held for sale. As discussed in Note 3, effective January 1, 2014, we adopted ASU 2014-08, which revised the definition of a discontinued operation. In the segment presentation above, the current year and prior year operating results for apartment communities sold during 2014 are presented within the Corporate and Amounts Not Allocated to Segments column. The operating results for the three months ended March 31, 2013, for apartment communities sold through December 31, 2013, are presented within discontinued operations and are accordingly excluded from the segment presentation above.