Equity - Noncontrolling Interests Narrative (Details) $ in Thousands, shares in Millions		12 Months Ended
	Oct. 07, 2015 USD ($) property	Dec. 31, 2017 USD ($) entity shares	Dec. 31, 2016 USD ($)
Noncontrolling Interest [Line Items]
Non-managing member unitholders		$ 176,888	$ 179,336
HCP Ventures V
Noncontrolling Interest [Line Items]
Noncontrolling interest (as a percent)	49.00%
Consideration received from sale of noncontrolling interest in HCP Ventures V	$ 110,000
HCP Ventures V
Noncontrolling Interest [Line Items]
Number of properties | property	11
Noncontrolling Interests
Noncontrolling Interest [Line Items]
Non-managing members DownREIT units outstanding | shares		4
Conversion of DownREIT units (in shares) | shares		7
Number of DownREIT LLCs | entity		5
Non-managing member unitholders		$ 177,000
DownREIT unit, fair value		$ 173,000