Real Estate Disposition Activities (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014 community	Sep. 30, 2013	Sep. 30, 2014 community	Sep. 30, 2013
Summary of income from discontinued operations
Number of Apartment Communities Sold			3
Number Of Communities Held For Sale	1		1
Gain on sale of discontinued operations	$ 0	$ 0	$ 37,869	$ 118,173
Gain on sale of communities			98,814	118,413
Avalon Valley [Member]
Summary of income from discontinued operations
Apartment homes			268
Net proceeds			53,325
Gain on sale of discontinued operations			37,869
Oakwood Philadelphia [Member]
Summary of income from discontinued operations
Apartment homes	80
Net proceeds	28,875
Gain on sale of communities	3,268
Avalon Danvers [Member]
Summary of income from discontinued operations
Apartment homes	433
Net proceeds	108,500
Gain on sale of communities	$ 41,021