The percentage of debt instruments tendered.

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Secured debt including debt on real estate held for sale.

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Secured debt.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after accumulated amortization, of debt premium.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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SECURED AND UNSECURED DEBT, NET - Debt Covenants (Details)				1 Months Ended		3 Months Ended		6 Months Ended
	Jul. 21, 2020 USD ($)	Jul. 14, 2020 USD ($)	Jun. 30, 2020 USD ($) loan	Feb. 29, 2020 USD ($)	Jul. 31, 2019 USD ($)	Jun. 30, 2020 USD ($) loan	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) loan	Jun. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Oct. 31, 2019 USD ($)
Fixed and variable rate debt
Amortization of financing costs						$ 1,100,000	$ 1,100,000	$ 2,100,000	$ 2,100,000
Secured Debt
Secured debt amount which encumbers real estate owned based upon book value			$ 2,000,000,000.0			$ 2,000,000,000.0		$ 2,000,000,000.0
Percentage of secured debt which encumbers real estate owned based upon book value			16.00%			16.00%		16.00%
Secured debt amount of real estate owned which is unencumbered			$ 10,700,000,000			$ 10,700,000,000		$ 10,700,000,000
Percentage of secured debt of real estate owned which is unencumbered			84.00%			84.00%		84.00%
Interest rate at end of the period								3.24%
Borrowings outstanding at end of period			$ 2,900,000			$ 2,900,000		$ 2,900,000			$ 2,900,000
Unamortized net premium			30,200,000			30,200,000		$ 30,200,000			35,300,000
Weighted Average Interest Rate								3.24%
Unsecured Debt
Secured Debt
Interest rate at end of the period								3.26%
Credit facility interest rate								90
Basis points added to to variable rate								90.00%
Weighted Average Interest Rate								3.26%
Unsecured Debt \| Maximum
Secured Debt
Basis points added to to variable rate								165.00%
Unsecured Debt \| Minimum
Secured Debt
Basis points added to to variable rate								80.00%
Unsecured Working Capital Credit Facility
Secured Debt
Credit facilities with aggregate commitment			75,000,000			75,000,000		$ 75,000,000			75,000,000
Interest rate at end of the period								0.99%
Credit facility interest rate								82.5
Borrowings outstanding at end of period			17,180,000			17,180,000		$ 17,180,000			16,583,000
Weighted Average Interest Rate								0.99%
Unsecured Working Capital Credit Facility \| Maximum
Secured Debt
Basis points added to to variable rate								145.00%
Unsecured Working Capital Credit Facility \| Minimum
Secured Debt
Basis points added to to variable rate								75.00%
3.75% Medium-Term Notes Due July 2024
Secured Debt
Interest rate at end of the period								3.75%
Portion of medium term note subject to interest rate swaps			100,000,000.0			100,000,000.0		$ 100,000,000.0
Long-term Debt, Weighted Average Interest Rate								3.69%
Senior Notes			299,583,000			299,583,000		$ 299,583,000			299,530,000
Weighted Average Interest Rate								3.75%
3.75% Medium-Term Notes Due July 2024 \| Cash Tender Offer
Secured Debt
Principal outstanding		$ 300,000,000.0
Interest rate		3.75%
Make-whole amount		$ 24,000,000.0
Tendered value		$ 116,900,000
Tendered percentage		39.00%
Tender offer consideration per each $1,000		$ 1,101.92
2.10% Medium Term Note Due August 1, 2032
Secured Debt
Interest rate	2.10%
Debt	$ 400,000,000.0
Price as percentage of principal amount	99.894
4.64% Secured Debt Due in 2023
Secured Debt
Interest rate	4.64%
Repayment of debt	$ 245,800,000
Mortgages Note Payable \| Fixed Rate Debt
Secured Debt
Principal outstanding			855,585,000			$ 855,585,000		$ 855,585,000			884,869,000
Interest rate at end of the period								3.60%
Weighted Average Interest Rate								3.60%
Mortgage Note Payable Matures on November 2020 \| Fixed Rate Debt
Secured Debt
Refinanced debt			$ 79,500,000
Interest rate			4.35%			4.35%		4.35%
Debt Assumed As Part of Acquisition
Secured Debt
Amortization of debt discount (Premium)						$ 2,500,000	$ 600,000	$ 5,100,000	$ 1,100,000
Tax-exempt secured notes payable \| Variable Rate Debt
Secured Debt
Principal outstanding			$ 27,000,000			27,000,000		$ 27,000,000			27,000,000
Interest rate at end of the period								0.85%
Weighted Average Interest Rate								0.85%
Credit facilities \| Fixed Rate Debt
Secured Debt
Principal outstanding			$ 202,254,000			$ 202,254,000		$ 202,254,000			204,590,000
Interest rate at end of the period								4.90%
Weighted Average Interest Rate								4.90%
Tax-exempt secured notes payable \| Variable Rate Debt
Secured Debt
Notes payable maximum interest rates range			0.85%			0.85%		0.85%
Revolving Credit Facility
Secured Debt
Basis points added to to variable rate								82.50%
Commitment fee								15.00%
Revolving Credit Facility \| Maximum
Secured Debt
Basis points added to to variable rate								145.00%
Commitment fee								30.00%
Revolving Credit Facility \| Minimum
Secured Debt
Basis points added to to variable rate								75.00%
Commitment fee								10.00%
4.00% Medium-Term Note due October 2025
Secured Debt
Interest rate at end of the period								4.00%
Portion of medium term note subject to interest rate swaps			$ 200,000,000.0			$ 200,000,000.0		$ 200,000,000.0
Senior Notes			299,638,000			299,638,000		$ 299,638,000			299,604,000
Weighted Average Interest Rate								4.00%
4.40% Medium-Term Notes due January 2029
Secured Debt
Interest rate at end of the period								4.40%
Portion of medium term note subject to interest rate swaps			150,000,000.0			150,000,000.0		$ 150,000,000.0
Long-term Debt, Weighted Average Interest Rate								4.27%
Senior Notes			299,995,000			299,995,000		$ 299,995,000			299,995,000
Weighted Average Interest Rate								4.40%
2.95% Medium-Term Note due September 2026
Secured Debt
Interest rate at end of the period								2.95%
Senior Notes			300,000,000			300,000,000		$ 300,000,000			300,000,000
Weighted Average Interest Rate								2.95%
3.20% Medium-Term Notes due January 2030
Secured Debt
Interest rate at end of the period								3.20%
Interest rate				3.20%	3.20%							3.20%
Long-term Debt, Weighted Average Interest Rate					3.42%
Senior Notes			613,099,000	$ 600,000,000.0		613,099,000		$ 613,099,000			402,281,000
Debt				$ 200,000,000.0	$ 300,000,000.0							$ 100,000,000.0
Price as percentage of principal amount				105.660
Weighted Average Interest Rate								3.20%
3.00% Medium-Term Notes due August 2031
Secured Debt
Interest rate at end of the period								3.00%
Senior Notes			$ 398,925,000			$ 398,925,000		$ 398,925,000			398,877,000
Weighted Average Interest Rate								3.00%
3.24% Notes due on 2030
Secured Debt
Interest rate			3.24%			3.24%		3.24%
Debt					$ 300,000,000.0							$ 100,000,000.0
Medium-Term Notes Due August 2031
Secured Debt
Debt			$ 150,000,000.0			$ 150,000,000.0		$ 150,000,000.0
Medium-Term Notes Due August 2031 \| Weighted Average
Secured Debt
Interest rate at end of the period								3.01%
Weighted Average Interest Rate								3.01%
3.10% senior unsecured notes due 2034 \| Weighted Average
Secured Debt
Interest rate at end of the period								3.13%
Weighted Average Interest Rate								3.13%
Unsecured Commercial Bank Credit Facility
Secured Debt
Credit facilities with aggregate commitment			2,000,000,000.0			2,000,000,000.0		$ 2,000,000,000.0
Unsecured Commercial Bank Credit Facility \| Unsecured Revolving credit facility due 2023
Secured Debt
Credit facilities with aggregate commitment			$ 1,100,000,000			$ 1,100,000,000		$ 1,100,000,000
Number of Extensions of loan \| loan			2			2		2
Extension period of option on loan								6 months
Unsecured Commercial Bank Credit Facility \| Revolving Credit Facility
Secured Debt
Credit facilities with aggregate commitment			$ 1,100,000,000			$ 1,100,000,000		$ 1,100,000,000			1,100,000,000
Credit facilities
Secured Debt
Principal outstanding			$ 202,300,000			$ 202,300,000		$ 202,300,000
Credit facilities \| Fixed Rate Debt
Secured Debt
Interest rate at end of the period								4.90%
Weighted Average Interest Rate								4.90%
Credit facilities \| Fair Value, Measurements, Recurring \| Carrying Amount \| Credit facilities \| Fixed Rate Debt
Secured Debt
Principal outstanding											218,490,000
Mortgages Note Payable \| Fixed Rate Debt \| Maximum
Secured Debt
Notes payable maximum interest rates range			4.35%			4.35%		4.35%
Mortgages Note Payable \| Fixed Rate Debt \| Minimum
Secured Debt
Notes payable maximum interest rates range			2.70%			2.70%		2.70%
Mortgages Note Payable \| Fair Value, Measurements, Recurring \| Carrying Amount \| Mortgages Note Payable \| Fixed Rate Debt
Secured Debt
Principal outstanding			$ 874,177,000			$ 874,177,000		$ 874,177,000			906,228,000
United Dominion Realty L.P.
Secured Debt
Notes payable maximum interest rates range			3.24%			3.24%		3.24%
Interest rate at end of the period								2.54%
Weighted Average Interest Rate								2.54%
United Dominion Realty L.P. \| Fixed Rate Debt
Secured Debt
Interest rate at end of the period								3.10%
Weighted Average Interest Rate								3.10%
United Dominion Realty L.P. \| Variable Rate Debt
Secured Debt
Interest rate at end of the period								0.85%
Weighted Average Interest Rate								0.85%
United Dominion Realty L.P. \| 3.75% Medium-Term Notes Due July 2024 \| Cash Tender Offer
Secured Debt
Principal outstanding		$ 300,000,000.0
Interest rate		3.75%
Make-whole amount		$ 24,000,000.0
Tendered value		$ 116,900,000
Tendered percentage		39.00%
Tender offer consideration per each $1,000		$ 1,101.92
United Dominion Realty L.P. \| 2.10% Medium Term Note Due August 1, 2032
Secured Debt
Interest rate	2.10%
Price as percentage of principal amount	99.894
United Dominion Realty L.P. \| 4.64% Secured Debt Due in 2023
Secured Debt
Interest rate	4.64%
Repayment of debt	$ 245,800,000
United Dominion Realty L.P. \| Mortgages Note Payable
Secured Debt
Principal outstanding			$ 72,500,000			$ 72,500,000		$ 72,500,000
Interest rate			3.10%			3.10%		3.10%
United Dominion Realty L.P. \| Mortgages Note Payable \| Fixed Rate Debt
Secured Debt
Principal outstanding			$ 72,500,000			$ 72,500,000		$ 72,500,000			72,500,000
Interest rate at end of the period								3.10%
Weighted Average Interest Rate								3.10%
United Dominion Realty L.P. \| Tax-exempt secured notes payable \| Variable Rate Debt
Secured Debt
Principal outstanding			27,000,000			27,000,000		$ 27,000,000			27,000,000
Interest rate at end of the period								0.85%
Weighted Average Interest Rate								0.85%
United Dominion Realty L.P. \| Unsecured Commercial Paper
Secured Debt
Borrowings outstanding at end of period			$ 185,000,000.0			$ 185,000,000.0		$ 185,000,000.0			$ 300,000,000.0
Forecast \| Mortgage Note Payable Matures on 2031 \| Fixed Rate Debt
Secured Debt
Principal outstanding										$ 160,900,000
Interest rate										2.62%