Financial Instruments and Fair Value Measurements - Schedule of Items Measured at Fair Value on Nonrecurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Impairment charges				$ 85,598	$ 1,721
Fair Value, Measurements, Nonrecurring
Derivatives, Fair Value [Line Items]
Impairment charges				85,598	1,721
Fair Value, Measurements, Nonrecurring | Acadia Realty Trust
Derivatives, Fair Value [Line Items]
Impairment charges				$ 20,594	$ 395
Fair Value, Measurements, Nonrecurring | Cortlandt Crossing, Mohegan Lake, NY | Fund III | Level 3 Inputs Projections
Derivatives, Fair Value [Line Items]
Triggering Event	Reduced holding period, reduced projected operating income
Impairment charges	$ 27,402
Fair Value, Measurements, Nonrecurring | Cortlandt Crossing, Mohegan Lake, NY | Acadia Realty Trust | Fund III | Level 3 Inputs Projections
Derivatives, Fair Value [Line Items]
Impairment charges	$ 6,726
Fair Value, Measurements, Nonrecurring | 654 Broadway, New York, NY | Fund III | Level 3 Inputs Projections
Derivatives, Fair Value [Line Items]
Triggering Event	Reduced holding period
Impairment charges	$ 6,398
Fair Value, Measurements, Nonrecurring | 654 Broadway, New York, NY | Acadia Realty Trust | Fund III | Level 3 Inputs Projections
Derivatives, Fair Value [Line Items]
Impairment charges	$ 1,570
Fair Value, Measurements, Nonrecurring | 146 Geary Street, San Francisco, CA | Fund IV | Level 3 Inputs Projections
Derivatives, Fair Value [Line Items]
Triggering Event	Reduced holding period, reduced projected operating income
Impairment charges	$ 6,718
Fair Value, Measurements, Nonrecurring | 146 Geary Street, San Francisco, CA | Acadia Realty Trust | Fund IV | Level 3 Inputs Projections
Derivatives, Fair Value [Line Items]
Impairment charges	$ 1,553
Fair Value, Measurements, Nonrecurring | 801 Madison Avenue, New York, NY | Fund IV | Level 3 Inputs Projections
Derivatives, Fair Value [Line Items]
Triggering Event	Reduced holding period, reduced projected operating income
Impairment charges	$ 11,031
Fair Value, Measurements, Nonrecurring | 801 Madison Avenue, New York, NY | Acadia Realty Trust | Fund IV | Level 3 Inputs Projections
Derivatives, Fair Value [Line Items]
Impairment charges	$ 2,551
Fair Value, Measurements, Nonrecurring | 717 N. Michigan Avenue, Chicago, IL | Fund IV | Level 3 Inputs Projections
Derivatives, Fair Value [Line Items]
Triggering Event				Reduced holding period, reduced projected operating income
Impairment charges				$ 17,392
Fair Value, Measurements, Nonrecurring | 717 N. Michigan Avenue, Chicago, IL | Acadia Realty Trust | Fund IV | Level 3 Inputs Projections
Derivatives, Fair Value [Line Items]
Impairment charges				$ 4,021
Fair Value, Measurements, Nonrecurring | 110 University, New York, NY | Fund IV | Level 3 Inputs Projections
Derivatives, Fair Value [Line Items]
Triggering Event				Reduced holding period, reduced projected operating income
Impairment charges				$ 16,238
Fair Value, Measurements, Nonrecurring | 110 University, New York, NY | Acadia Realty Trust | Fund IV | Level 3 Inputs Projections
Derivatives, Fair Value [Line Items]
Impairment charges				$ 3,754
Fair Value, Measurements, Nonrecurring | Fifth Wall Investment | Core Portfolio | Level 3 Inputs Fair Value of Net Assets Projections
Derivatives, Fair Value [Line Items]
Triggering Event				Decline in fair value
Impairment charges				$ 419
Fair Value, Measurements, Nonrecurring | Fifth Wall Investment | Acadia Realty Trust | Core Portfolio | Level 3 Inputs Fair Value of Net Assets Projections
Derivatives, Fair Value [Line Items]
Impairment charges				$ 419
Fair Value, Measurements, Nonrecurring | 210 Bowery Residential Units | Fund IV | Level 3 Inputs Contract Sales Price
Derivatives, Fair Value [Line Items]
Triggering Event		Reduced selling price
Impairment charges		$ 321
Fair Value, Measurements, Nonrecurring | 210 Bowery Residential Units | Fund IV | Level 3 Inputs Offering Price
Derivatives, Fair Value [Line Items]
Triggering Event			Reduced selling price
Impairment charges			$ 1,400
Fair Value, Measurements, Nonrecurring | 210 Bowery Residential Units | Acadia Realty Trust | Fund IV | Level 3 Inputs Contract Sales Price
Derivatives, Fair Value [Line Items]
Impairment charges		$ 74
Fair Value, Measurements, Nonrecurring | 210 Bowery Residential Units | Acadia Realty Trust | Fund IV | Level 3 Inputs Offering Price
Derivatives, Fair Value [Line Items]
Impairment charges			$ 321