Commitments, Contingencies and Guarantees - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) ft² apartment building
Other Commitments [Line Items]
Number of buildings containing asbestos | building	32
Unconsolidated Funds
Other Commitments [Line Items]
Number of buildings containing asbestos | apartment	500
Development Projects
Other Commitments [Line Items]
Aggregate remaining contractual commitment | $	$ 211.4
Development Projects | California
Other Commitments [Line Items]
Number of apartments under construction | apartment	376
Development Projects | Hawaii
Other Commitments [Line Items]
Square footage of office tower conversion (sq ft) | ft²	490,000
Repositionings, Capital Expenditure Projects, and Tenant Improvements
Other Commitments [Line Items]
Aggregate remaining contractual commitment | $	$ 25.5