Real Estate Investments - Acquisitions and Sales Of Real Estate (Details)	1 Months Ended			3 Months Ended				12 Months Ended
	Dec. 31, 2019 USD ($) unit	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) unit	Sep. 30, 2019 USD ($) unit	Jun. 30, 2019 USD ($) unit	Mar. 31, 2019 USD ($) unit	Dec. 31, 2019 USD ($) community unit	Dec. 31, 2018 USD ($) community unit
Schedule of Equity Method Investments [Line Items]
Number of units acquired | unit								849
Purchase Price								$ 373,300,000	$ 35,400,000
Investment in real estate	$ 14,038,142,000			$ 14,038,142,000				14,038,142,000
Encumbrance	990,667,000			990,667,000				990,667,000
Land and Land Improvements
Schedule of Equity Method Investments [Line Items]
Purchase Price								72,400,000
Building and Improvements
Schedule of Equity Method Investments [Line Items]
Purchase Price								402,400,000
Prepaid Expenses and Other Assets
Schedule of Equity Method Investments [Line Items]
Purchase Price								3,300,000
Mortgage Notes Payable
Schedule of Equity Method Investments [Line Items]
Purchase Price								149,000,000.0
One South Market
Schedule of Equity Method Investments [Line Items]
Limited partnership interest			45.00%
Investment in real estate			$ 179,000,000.0				$ 179,000,000.0
Encumbrance			$ 86,000,000.0				$ 86,000,000.0
Brio
Schedule of Equity Method Investments [Line Items]
Purchase Price		$ 164,900,000
Encumbrance		$ 98,700,000				$ 98,700,000
Hidden Valley
Schedule of Equity Method Investments [Line Items]
Purchase Price	$ 24,200,000
Limited partnership interest	25.00%
Investment in real estate	$ 97,000,000.0			97,000,000.0				97,000,000.0
Encumbrance	$ 29,700,000			$ 29,700,000				$ 29,700,000
Apartment Building
Schedule of Equity Method Investments [Line Items]
Number of communities acquired | community								4	1
Number of units acquired | unit								849	166
Apartment Building | One South Market
Schedule of Equity Method Investments [Line Items]
Number of units acquired | unit							312
Essex Ownership Percentage			100.00%				100.00%
Purchase Price							$ 80,600,000
Apartment Building | Brio
Schedule of Equity Method Investments [Line Items]
Number of units acquired | unit						300
Purchase Price						$ 164,900,000
Apartment Building | Township
Schedule of Equity Method Investments [Line Items]
Number of units acquired | unit					132
Essex Ownership Percentage					100.00%
Purchase Price					$ 88,700,000
Apartment Building | Pure Redmond
Schedule of Equity Method Investments [Line Items]
Number of units acquired | unit				105
Essex Ownership Percentage	100.00%			100.00%				100.00%
Purchase Price				$ 39,100,000
Apartment Building | Hidden Valley
Schedule of Equity Method Investments [Line Items]
Number of units acquired | unit	324