Business Segments (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Segment Reporting Information [Line Items]
Total consolidated assets	$ 6,079,413		$ 6,401,380
Conventional Real Estate Operations [Member]
Segment Reporting Information [Line Items]
Total consolidated assets	4,793,472		4,837,236
Affordable Real Estate Operations [Member]
Segment Reporting Information [Line Items]
Total consolidated assets	382,091		466,678
Proportionate Adjustments [Member]
Segment Reporting Information [Line Items]
Total consolidated assets	428,376	[1]	634,858	[1]
Corporate and Amounts Not Allocated to Segments [Member]
Segment Reporting Information [Line Items]
Total consolidated assets	$ 475,474		$ 462,608

[1] Represents adjustments for the noncontrolling interests in consolidated real estate partnerships’ share of the assets of our consolidated apartment communities, which are excluded from our measurement of segment financial condition, and our share of the assets of our unconsolidated real estate partnerships, which are included in our measure of segment financial condition.