Leases - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) Property CorporateOfficeLease	Dec. 31, 2019
Corporate Office Leases [Member]
Operating Leased Assets [Line Items]
Number of operating leases | CorporateOfficeLease	9
Ground Leases [Member]
Operating Leased Assets [Line Items]
Unsecured borrowing rates for actual pricing period used for calculating discount rate	30 years
Number of operating properties | Property	14
COVID-19 [Member]
Operating Leased Assets [Line Items]
Write-off of straight-line rent receivables	$ 13.2
Maximum [Member] | Corporate Office Leases [Member]
Operating Leased Assets [Line Items]
Discount rate	3.90%
Remaining lease terms	10 years
Lease expiration dates (inclusive of applicable extension options)	2042
Maximum [Member] | Ground Leases [Member]
Operating Leased Assets [Line Items]
Discount rate	5.50%
Operating lease expiration year	2118
Minimum [Member] | Corporate Office Leases [Member]
Operating Leased Assets [Line Items]
Discount rate	3.30%
Lease expiration dates (inclusive of applicable extension options)	2021
Minimum [Member] | Ground Leases [Member]
Operating Leased Assets [Line Items]
Discount rate	4.40%
Operating lease expiration year	2042
Residential Apartment Leases [Member]
Operating Leased Assets [Line Items]
Percentage of rental income	98.00%	97.00%
Residential Apartment Leases [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Retail leases term	12 months
Non-residential Leases [Member]
Operating Leased Assets [Line Items]
Percentage of rental income	2.00%	3.00%
Decrease in rental revenues	$ 7.3
Non-residential Leases [Member] | Maximum [Member]
Operating Leased Assets [Line Items]
Retail leases term	10 years
Non-residential Leases [Member] | Minimum [Member]
Operating Leased Assets [Line Items]
Retail leases term	5 years