Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) Property ApartmentUnit $ / shares	Dec. 31, 2019 USD ($) $ / shares	Dec. 31, 2018 USD ($) $ / shares	Jan. 01, 2019 USD ($)
Value of furniture and fixtures minimum range	$ 15,000
Value of furniture and fixtures maximum range	$ 40,000
Lease intangibles, average term	6 months
Capitalized costs development and renovation	$ 12,100,000	$ 14,200,000	$ 13,200,000
Lessee, finance lease, description	The Company is a lessor for its residential and non-residential leases and is a lessee for its corporate headquarters and regional offices and ground leases for land underlying current operating properties or projects under development.  If applicable, lease agreements must be evaluated to determine the accounting treatment as a finance or operating lease in accordance with the lease standard.  A lease is classified as a finance lease if it meets any of the following criteria:  (a) Ownership of the underlying asset is transferred to the lessee by the end of the lease term; (b) the lessee has and is reasonably certain to exercise an option to purchase the underlying asset; (c) the lease term is for the major part of the remaining economic life of the underlying asset; (d) the present value of future minimum lease payments is equal to substantially all of the fair value of the underlying asset; and (e) the underlying asset is expected to have no alternative use to the lessor at the end of the lease term due to its specialized nature.
Lessee, finance lease residual value guarantee, description	the present value of future minimum lease payments is equal to substantially all of the fair value of the underlying asset
Common Stock, Par or Stated Value Per Share | $ / shares	$ 0.01	$ 0.01	$ 0.01
Provision for income tax	$ 852,000	$ (2,281,000)	$ 878,000
Remaining AMT refund received	1,600,000
Land and depreciable property net	13,800,000,000	13,700,000,000
Right-of-use assets	499,287,000	512,774,000		$ 434,200,000
Lease liabilities	$ 329,130,000	331,334,000		$ 278,300,000
Properties | Property	304
Noncontrolling Interests – Partially Owned Properties	$ 4,673,000	$ 1,183,000
Apartment units | ApartmentUnit	77,889
Partially Owned Properties – Consolidated
Properties | Property	16
Noncontrolling Interests – Partially Owned Properties	$ 4,700,000
Apartment units | ApartmentUnit	3,399
Limited Life Partnership Properties [Member]
Properties | Property	3
Noncontrolling Interests – Partially Owned Properties	$ (5,500,000)
Noncontrolling interests settlement value	72,800,000
Federal [Member]
Provision for income tax	$ 0
Minimum [Member] | Retail Commercial Leases [Member]
Retail leases term	5 years
Maximum [Member] | Retail Commercial Leases [Member]
Retail leases term	10 years
Furniture and Fixtures [Member] | Minimum [Member]
Property, plant and equipment, estimated useful lives	5 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, plant and equipment, estimated useful lives	10 years
Building [Member]
Property, plant and equipment, estimated useful lives	30 years
Replacements [Member] | Minimum [Member]
Property, plant and equipment, estimated useful lives	5 years
Replacements [Member] | Maximum [Member]
Property, plant and equipment, estimated useful lives	10 years
Renovations and Improvements Minimum [Member] | Minimum [Member]
Property, plant and equipment, estimated useful lives	5 years
Renovations and Improvements Minimum [Member] | Maximum [Member]
Property, plant and equipment, estimated useful lives	15 years