Co-investments - Summary of Investments (Details) $ in Thousands	1 Months Ended	6 Months Ended
	Jan. 31, 2020 community apartment	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Schedule of Equity Method Investments [Line Items]
Co-investments		$ 1,008,758	$ 1,335,339
Total operating and other co-investments, net
Schedule of Equity Method Investments [Line Items]
Co-investments		$ 368,259	743,461
CPPIB
Schedule of Equity Method Investments [Line Items]
Weighted average company ownership percentage		0.00%
Co-investments		$ 0	345,466
Wesco I, Wesco III, Wesco IV, and Wesco V
Schedule of Equity Method Investments [Line Items]
Weighted average company ownership percentage		51.00%
Co-investments		$ 186,509	216,756
BEXAEW, BEX II, BEX III, and BEX IV
Schedule of Equity Method Investments [Line Items]
Weighted average company ownership percentage		50.00%
Co-investments		$ 155,759	160,888
Other
Schedule of Equity Method Investments [Line Items]
Weighted average company ownership percentage		47.00%
Co-investments		$ 25,991	20,351
Total predevelopment and development co-investments
Schedule of Equity Method Investments [Line Items]
Weighted average company ownership percentage		50.00%
Co-investments		$ 167,774	146,944
Total preferred interest co-investments
Schedule of Equity Method Investments [Line Items]
Co-investments		472,725	444,934
Total preferred interest co-investments | Investments in Majority-owned Subsidiaries
Schedule of Equity Method Investments [Line Items]
Co-investments		$ 77,300	$ 73,200
CPPIB interest
Schedule of Equity Method Investments [Line Items]
Investment interest acquired	45.00%
Apartment Building | CPPIB interest
Schedule of Equity Method Investments [Line Items]
Number of communities held by acquired investment | community	6
Number of units held by acquired investment | apartment	2,020