Segment Reporting (Schedule Of Assets For Each Of The Reportable Segments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Reconciling items, Assets	$ 94,641	$ 98,774
Total assets	4,153,206	3,634,703
Core Properties [Member]
Segment Reporting Information [Line Items]
Apartments owned, Assets	2,851,848	2,870,247
Non-Core Properties [Member]
Segment Reporting Information [Line Items]
Apartments owned, Assets	$ 1,206,717	$ 665,682