Mortgage Notes Payable (Details)	12 Months Ended
	Dec. 31, 2021 USD ($) property	Dec. 31, 2020 USD ($) property	Dec. 31, 2019
Debt Instrument [Line Items]
Total mortgage notes payable	$ 638,959,000	$ 643,550,000
Number of properties securing mortgage notes | property	12	12
Weighted average interest rate	2.70%	2.70%
Unamortized debt issuance expense	$ (1,500,000)	$ (1,800,000)
Monthly interest expense	2,300,000
Monthly principal amortization	300,000
Mortgage notes payable, net	$ 638,957,000	$ 643,550,000
Repayment of debt before the scheduled maturity date, prepayment penalties	The prepayment penalty on the majority of the Company’s mortgage notes payable are computed by the greater of (a) 1% of the amount of the principal being prepaid or (b) the present value of the principal being prepaid multiplied by the difference between the interest rate of the mortgage note and the stated yield rate on a U.S. treasury security which generally has an equivalent remaining term as the mortgage note.
Prepayment penalty, percent of principal prepaid	1.00%
Minimum
Debt Instrument [Line Items]
Remaining terms	1 year	1 year
Maximum
Debt Instrument [Line Items]
Remaining terms	25 years	26 years
Fixed rate mortgage notes payable
Debt Instrument [Line Items]
Total mortgage notes payable	$ 415,350,000	$ 419,323,000
Fixed rate mortgage notes payable | Total Return Swap Callable | Not Designated as Hedging Instrument
Debt Instrument [Line Items]
Derivative notional amount	224,400,000
Variable rate mortgage notes payable
Debt Instrument [Line Items]
Total mortgage notes payable	223,609,000	$ 224,227,000
Derivative notional amount	$ 224,400,000
Multifamily housing mortgage revenue bonds, variable interest rate (in hundredths)		1.10%	1.20%
Percentage of units subject to tenant income criteria (in hundredths)	20.00%
Secured debt
Debt Instrument [Line Items]
Total mortgage notes payable	$ 637,925,000
Debt instrument, unamortized premium	2,500,000	$ 3,900,000
Secured deeds of trust
Debt Instrument [Line Items]
Mortgage notes payable, net	$ 0	$ 0