Real Estate Disposition Activities (Details) ft² in Thousands, $ in Thousands	3 Months Ended			12 Months Ended			24 Months Ended
	Dec. 31, 2021 USD ($) ft² residential_condominium home community	Jun. 30, 2021 USD ($) home	Mar. 31, 2021 USD ($) home	Dec. 31, 2021 USD ($) ft² residential_condominium land_parcel community home	Dec. 31, 2020 USD ($) home	Dec. 31, 2019 USD ($) home	Dec. 31, 2021 USD ($) ft² residential_condominium community
Summary of income from discontinued operations
Gain on sale of communities				$ 602,235	$ 340,444	$ 166,105
Number of land parcels sold | land_parcel				1
Number of communities held for sale | community	1			1			1
Number of residential condominiums sold | residential_condominium				53			123
Number of residential condominiums remaining to be sold | residential_condominium	49			49			49
Gain on for-sale condominiums				$ 3,110	8,213	0
Other selling, general and administrative expense				4,087	5,662	$ 3,812
For-sale condominium inventory	$ 146,535			146,535	$ 267,219		$ 146,535
eaves Stamford
Summary of income from discontinued operations
Number of apartment homes sold | home			238
Gross sales price			$ 72,000
Net cash proceeds			$ 70,062
Avalon Norwalk
Summary of income from discontinued operations
Number of apartment homes sold | home		311
Gross sales price		$ 103,000
Net cash proceeds		$ 101,422
AVA Cortez Hill
Summary of income from discontinued operations
Number of apartment homes sold | home		299
Gross sales price		$ 96,500
Net cash proceeds		$ 94,648
Avalon Redmond Place
Summary of income from discontinued operations
Number of apartment homes sold | home		222
Gross sales price		$ 97,700
Net cash proceeds		$ 86,750
Avalon Bronxville
Summary of income from discontinued operations
Number of apartment homes sold | home		110
Gross sales price		$ 89,000
Net cash proceeds		$ 88,088
Avalon Glen Cove & Avalon Glen Cove North
Summary of income from discontinued operations
Number of apartment homes sold | home		367
Gross sales price		$ 126,000
Net cash proceeds		$ 125,564
eaves Lawrenceville
Summary of income from discontinued operations
Number of apartment homes sold | home	632
Gross sales price	$ 208,000
Net cash proceeds	$ 203,705
Avalon at Center Place
Summary of income from discontinued operations
Number of apartment homes sold | home	225
Gross sales price	$ 75,000
Net cash proceeds	$ 71,841
Other real estate
Summary of income from discontinued operations
Gross sales price				7,858
Net cash proceeds				$ 8,150
Wholly owned properties
Summary of income from discontinued operations
Number of apartment communities sold | community				9
Number of apartment homes sold | home				2,404	1,817	1,660
Sale of communities gross sales price				$ 867,200
Gain on sale of communities				602,235
Gross sales price				875,058	$ 634,250	$ 431,280
Net cash proceeds				850,230	$ 619,773	422,041
Repayments of secured debt						$ 21,700
The Park Loggia
Summary of income from discontinued operations
Net cash proceeds				$ 135,458
Number of residential units in development | residential_condominium	172			172			172
Commercial square feet | ft²	66			66			66
Gain on for-sale condominiums				$ 3,110