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Amount of investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

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Borrowings - Additional Information (Details)	1 Months Ended				12 Months Ended
Borrowings - Additional Information (Details)	Sep. 30, 2021 USD ($)	Aug. 31, 2021 USD ($)	Jul. 31, 2021 USD ($)	Feb. 28, 2021 ApartmentUnit	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage					3.40%
Commercial Paper Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Payment Terms					397
Debt Instrument, Face Amount					$ 0
Debt Instrument Face Amount					0
Maximum [Member] \| Commercial Paper Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount					500,000,000.0
Debt Instrument Face Amount					$ 500,000,000.0
Secured Debt [Member] \| Fixed Rate Debt Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date					Dec. 31, 2048
Debt Instrument, Interest Rate, Effective Percentage					4.40%
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate					$ 368,600,000
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage					3.30%
Unsecured Debt [Member] \| Fixed Rate Debt Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date					Mar. 04, 2029
Debt Instrument, Face Amount					$ 4,175,000,000	$ 3,922,000,000
Debt Instrument, Interest Rate, Effective Percentage					3.30%
Debt Instrument Face Amount					$ 4,175,000,000	$ 3,922,000,000
Unsecured Debt [Member] \| Years to Maturity [Member] \| Fixed Rate Debt Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Term					7 years 1 month 6 days
Unsecured Debt [Member] \| Other Non operating Income ExpenseMember
Debt Instrument [Line Items]
Prepayment Penalties And Write-offs Of Unamortized Costs					$ 13,400,000
Unsecured Debt [Member] \| Minimum [Member] \| Fixed Rate Debt Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Term					5 years
Unsecured Debt [Member] \| Maximum [Member] \| Fixed Rate Debt Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Term					30 years
Unsecured Debt [Member] \| $1 Billion Unsecured Revolving Credit Faciltiy [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity					$ 1,000,000,000.0
Line of Credit Facility, Maximum Borrowing Capacity					$ 1,500,000,000
Debt Instrument, Maturity Date					2023-05-31
Line of Credit Facility, Amount Outstanding					$ 0
Letters of Credit Outstanding, Amount					$ 4,000.0
Unsecured Debt [Member] \| $1 Billion Unsecured Revolving Credit Faciltiy [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate					0.75%
Unsecured Debt [Member] \| $1 Billion Unsecured Revolving Credit Faciltiy [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate					1.45%
Unsecured Debt [Member] \| Public Income Notes [Member] \| Fixed Rate Debt Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 4,200,000,000
Debt Instrument Face Amount					4,200,000,000
Unsecured Debt [Member] \| Private Placement [Member]
Debt Instrument [Line Items]
Retirement of tranche of Senior Unsecured Notes			$ 72,800,000
Unsecured Debt [Member] \| Maturing in September 2026, Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Payment Terms		Interest on the 2026 Notes is payable semi-annually in arrears on March 15 and September 15 of each year beginning March 15, 2022
Debt Instrument, Interest Rate, Stated Percentage		1.10%
Debt Instrument, Interest Rate, Effective Percentage		1.191%
Debt Instrument, Redemption Price, Percentage		99.553%
Debt Issuance Costs, Gross		$ 3,100,000
Proceeds from Debt, Net of Issuance Costs		296,900,000
Unsecured Debt [Member] \| Maturing in September 2026, Senior Notes [Member] \| Fixed Rate Debt Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		300,000,000
Debt Instrument Face Amount		$ 300,000,000
Unsecured Debt [Member] \| Maturing in November 2022, Tranche of Senior Notes [Member]
Debt Instrument [Line Items]
Retirement of tranche of Senior Unsecured Notes	$ 117,000,000.0
Unsecured Debt [Member] \| Maturing in December 2022, Tranche of Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	250,000,000.0
Retirement of tranche of Senior Unsecured Notes	125,000,000.0
Debt Instrument Face Amount	250,000,000.0
Unsecured Debt [Member] \| Maturing in July 2023, Tranche of Senior Notes [Member]
Debt Instrument [Line Items]
Retirement of tranche of Senior Unsecured Notes	12,300,000
Unsecured Debt [Member] \| Maturing in November 2024, Tranche of Senior Notes [Member]
Debt Instrument [Line Items]
Retirement of tranche of Senior Unsecured Notes	$ 20,000,000.0
Unsecured Debt [Member] \| Maturing in September 2051, Six Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Payment Terms		Interest on the 2051 Notes is payable semi-annually in arrears on March 15 and September 15 of each year beginning March 15, 2022
Debt Instrument, Face Amount		$ 300,000,000
Debt Instrument, Interest Rate, Stated Percentage		2.875%
Debt Instrument, Interest Rate, Effective Percentage		2.946%
Debt Instrument, Redemption Price, Percentage		98.588%
Debt Instrument Face Amount		$ 300,000,000
Debt Issuance Costs, Gross		6,900
Proceeds from Debt, Net of Issuance Costs		$ 293,100,000
Maturing July 2020, Three Property Mortgage [Member] \| Secured Debt [Member]
Debt Instrument [Line Items]
Repayments of Secured Debt					$ 118,600,000
Number of Apartment Communities \| ApartmentUnit				8