Real Estate Disposition Activities (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) community land_parcel home	Mar. 31, 2018 USD ($)
Summary of income from discontinued operations
Gain on sale of communities	$ 14,835	$ 0
Number of Land Parcels Sold | land_parcel	2
Number of communities held for sale | community	1
Oakwood Arlington [Member]
Summary of income from discontinued operations
Number of Apartment Homes Sold | home	184
Proceeds from sale of real estate	$ 70,000
Gain on sale of communities	16,382
Land Parcel [Member]
Summary of income from discontinued operations
Proceeds from sale of real estate	3,680
Gain on sale of communities	$ 224