Fair Value - Classification Between the Three Levels of the Fair Value Hierarchy (Details) - Recurring basis - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Estimate of Fair Value Measurement
Financial Instruments Measured/Discussed at Fair Value
Equity Securities	$ 29,236	$ 27,027
Notes Receivable, net	81,150	28,860
Total Assets	134,573	56,342
DownREIT units		1,211
Total Liabilities	6,967,850	7,423,876
Unsecured notes | Estimate of Fair Value Measurement
Financial Instruments Measured/Discussed at Fair Value
Indebtedness	6,313,990	6,653,681
Secured Debt, Commercial Paper Program and Variable Rate Unsecured Indebtedness | Estimate of Fair Value Measurement
Financial Instruments Measured/Discussed at Fair Value
Indebtedness	653,860	768,984
Interest Rate Caps | Non-designated Hedges | Estimate of Fair Value Measurement
Financial Instruments Measured/Discussed at Fair Value
Derivative assets	199	455
Interest Rate Swaps | Cash Flow Hedges | Estimate of Fair Value Measurement
Financial Instruments Measured/Discussed at Fair Value
Derivative assets	23,988
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Instruments Measured/Discussed at Fair Value
Total Assets	0	0
DownREIT units		1,211
Total Liabilities	6,313,990	6,654,892
Quoted Prices in Active Markets for Identical Assets (Level 1) | Unsecured notes
Financial Instruments Measured/Discussed at Fair Value
Indebtedness	6,313,990	6,653,681
Significant Other Observable Inputs (Level 2)
Financial Instruments Measured/Discussed at Fair Value
Equity Securities	29,236	27,027
Notes Receivable, net	81,150	28,860
Total Assets	134,573	56,342
Total Liabilities	653,860	768,984
Significant Other Observable Inputs (Level 2) | Secured Debt, Commercial Paper Program and Variable Rate Unsecured Indebtedness
Financial Instruments Measured/Discussed at Fair Value
Indebtedness	653,860	768,984
Significant Other Observable Inputs (Level 2) | Interest Rate Caps | Non-designated Hedges
Financial Instruments Measured/Discussed at Fair Value
Derivative assets	199	455
Significant Other Observable Inputs (Level 2) | Interest Rate Swaps | Cash Flow Hedges
Financial Instruments Measured/Discussed at Fair Value
Derivative assets	23,988
Significant Unobservable Inputs (Level 3)
Financial Instruments Measured/Discussed at Fair Value
Total Assets	0	0
Total Liabilities	$ 0	$ 0