Significant Transactions During the Three Months Ended March 31, 2021 and Subsequent Events (Details)	1 Months Ended			3 Months Ended
	Mar. 31, 2021 USD ($) apartment	Feb. 28, 2021 USD ($) apartment	Jan. 31, 2021 USD ($)	Mar. 31, 2021 USD ($) shares	Mar. 31, 2020 USD ($)
Other Commitments [Line Items]
Revenue from disposition				$ 2,249,000	$ 2,617,000
Commitments to acquire equity method investment			$ 20,000,000.0
Preferred return rate			10.00%
Affiliated Entity | Related party bridge loan - Wesco I
Other Commitments [Line Items]
Notes receivable	$ 52,500,000			$ 52,500,000
Interest rate	2.55%
Common Stock
Other Commitments [Line Items]
Shares repurchased during period (in shares) | shares				40,000
Shares repurchased during period, value				$ 9,200,000
Purchase authority remaining under stock repurchase plan	$ 214,500,000			214,500,000
Stock repurchase plan amount	250,000,000.0			250,000,000.0
Preferred Equity Investment Property In Southern California
Other Commitments [Line Items]
Proceeds from partial redemption of co-investment	10,000,000.0
Joint Venture That Holds Property In Southern California
Other Commitments [Line Items]
Proceeds from partial redemption of co-investment	110,200,000
Early redemption fee	3,500,000
Essex Portfolio, L.P.
Other Commitments [Line Items]
Revenue from disposition				2,249,000	$ 2,617,000
Essex Portfolio, L.P. | Senior Notes | 2032 Notes
Other Commitments [Line Items]
Debt issued	$ 450,000,000.0			$ 450,000,000.0
Debt coupon rate	1.70%			1.70%
Debt offering price, percentage of par value	99.423%			99.423%
Park 20, San Mateo, CA
Other Commitments [Line Items]
Revenue from disposition		$ 113,000,000.0
Park 20, San Mateo, CA | Apartment Building
Other Commitments [Line Items]
Number of apartment units | apartment		197
Hidden Valley, Simi Valley, CA
Other Commitments [Line Items]
Revenue from disposition		$ 105,000,000.0
Gain on sale of properties		69,200,000
Repayments of debt		$ 29,700,000
Hidden Valley, Simi Valley, CA | Apartment Building
Other Commitments [Line Items]
Number of apartment units | apartment		324
Axis 2300, Irvine, CA
Other Commitments [Line Items]
Revenue from disposition	$ 57,500,000
Gain on sale of properties	$ 30,800,000
Axis 2300, Irvine, CA | Apartment Building
Other Commitments [Line Items]
Number of apartment units | apartment	115