Equity - Noncontrolling Interests Narrative (Details) $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) entity shares	Dec. 31, 2017 USD ($)
Noncontrolling Interest [Line Items]
Non-managing member unitholders	$ 176,751	$ 176,888
Noncontrolling Interests
Noncontrolling Interest [Line Items]
Non-managing members DownREIT units outstanding (in shares) | shares	4
Conversion of DownREIT units (in shares) | shares	7
Number of DownREIT LLCs (in entities) | entity	5
Non-managing member unitholders	$ 177,000
DownREIT unit, fair value	$ 185,000