Real Estate Disposition Activities (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) community	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) community home	Jun. 30, 2017 USD ($)
Summary of income from discontinued operations
Gain on sale of communities	$ 105,201	$ 44,067	$ 105,201	$ 132,016
Number of Communities Held for Sale | community	1		1
Avalon at Blue Hills and Avalon Canton at Blue Hills [Member]
Summary of income from discontinued operations
Number of Apartment Homes Sold | home			472
Proceeds from Sale of Real Estate			$ 131,250
Gain on sale of communities			$ 57,666
Eaves North Quincy [Member]
Summary of income from discontinued operations
Number of Apartment Homes Sold | home			224
Proceeds from Sale of Real Estate			$ 64,250
Gain on sale of communities			$ 18,055
Avalon Anaheim Stadium [Member]
Summary of income from discontinued operations
Number of Apartment Homes Sold | home			251
Proceeds from Sale of Real Estate			$ 111,600
Gain on sale of communities			$ 29,490