Organization and Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($) Properties State Property Community shares	Sep. 30, 2024 USD ($) shares	Sep. 30, 2025 USD ($) Properties State Property Community shares	Sep. 30, 2024 USD ($) shares	Dec. 31, 2028 Property	Dec. 31, 2027 Property	Dec. 31, 2026 Property	Dec. 31, 2025 Property	Dec. 31, 2024 USD ($) shares
Real Estate Properties [Line Items]
General Partners' Capital Account, Units Outstanding | shares	117,081,742	116,880,291	117,081,742	116,880,291
Number of Real Estate Properties | Community	293		293
Number of units under development community | Properties	2,242		2,242
Development and capital improvements in progress	$ 449,390		$ 449,390						$ 470,282
Number of States in which Entity Operates | State	16		16
Consolidated assets	$ 11,926,585		$ 11,926,585						11,812,369
Consolidated liabilities	5,912,283		5,912,283						$ 5,664,705
Real Estate Investments, Joint Ventures	$ 22,400		$ 22,400
Percentage Of Rental Revenue From Leasing Of Apartment Homes			94.00%
Percentage Of Reimbursable Revenue From Leasing Of Apartment Homes			5.00%
Percentage of Rental Revenue and Other Income From Non-leasing Activities			1.00%
Operating Lease, Right-of-Use Asset, Statement of Financial Position	Other assets		Other assets						Other assets
Operating Lease, Liability, Statement of Financial Position [Extensible Enumeration]	Accrued expenses and other liabilities		Accrued expenses and other liabilities
Operating Lease, Right-of-Use Asset	$ 38,700		$ 38,700						$ 40,500
Right-of-use Lease, Liability	24,793		24,793						26,100
Net proceeds from sale of marketable equity securities		$ 3,300	0	$ 9,975
Net realized / unrealized gain on sale		2,700		8,300
Marketable equity securities	2,700		2,700						3,300
Marketable Equity Securities [Member]
Real Estate Properties [Line Items]
Unrealized gains (losses)	(800)	(1,200)	(600)	(5,400)
Limited Partnership [Member]
Real Estate Properties [Line Items]
Investment Income		$ 500	6,000	$ 9,000
Investment Expense	4,300
Other Assets [Member]
Real Estate Properties [Line Items]
Real Estate Investments, Joint Ventures	76,000		76,000						62,200
Real Estate [Member] | Post Massachusetts Avenue [Member]
Real Estate Properties [Line Items]
Real Estate Investments, Joint Ventures	$ 41,900		$ 41,900						$ 41,700
Maximum [Member] | Accounting Standards Update 2016-02 [Member]
Real Estate Properties [Line Items]
Operating lease, term of contract	1 year		1 year
Development Properties [Member] | Scenario Forecast [Member]
Real Estate Properties [Line Items]
Number of Real Estate Properties | Property					1	1	4	1
Retail [Member]
Real Estate Properties [Line Items]
Number of Real Estate Properties | Property	35		35
M A A L P [Member]
Real Estate Properties [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest			97.50%	97.40%
Limited Partnership [Member]
Real Estate Properties [Line Items]
General Partners' Capital Account, Units Outstanding | shares	117,081,742		117,081,742						116,883,421
Number of Real Estate Properties | Property	1		1
Development and capital improvements in progress	$ 449,390		$ 449,390						$ 470,282
Consolidated assets	11,926,585		11,926,585						11,812,369
Consolidated liabilities	5,912,302		5,912,302						5,664,724
Net proceeds from sale of marketable equity securities			0	$ 9,975
Limited Partnership [Member] | Real Estate [Member] | Variable Interest Entity Primary Beneficiary [Member]
Real Estate Properties [Line Items]
Consolidated assets	530,800		530,800						432,200
Consolidated liabilities	$ 24,200		$ 24,200						$ 27,100
Limited Partnership [Member] | Minimum [Member]
Real Estate Properties [Line Items]
Percentage of ownership interests of all consolidated subsidiaries (percent)	80.00%		80.00%
Limited Partnership [Member] | Maximum [Member]
Real Estate Properties [Line Items]
Percentage of ownership interests of all consolidated subsidiaries (percent)	100.00%		100.00%
Limited Partnership [Member] | Development Properties [Member] | Costs Incurred To Date [Member]
Real Estate Properties [Line Items]
Development and capital improvements in progress	$ 543,200		$ 543,200