Schedule III Real Estate and Accumulated Depreciation - Narrative (Details) $ in Thousands	Dec. 31, 2017 USD ($) property
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]
Number of properties owned	82,570
Number of properties held-for-sale	236
Number of encumbered units held-for-sale	62
Amount of encumbrances held for sale | $	$ 9,575
Gross aggregate real estate for federal income tax purposes | $	$ 17,026,896