Equity - Narrative (Details) - USD ($)	3 Months Ended	9 Months Ended		12 Months Ended
Equity - Narrative (Details) - USD ($)	Sep. 30, 2025	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	280,000,000	280,000,000		280,000,000
Preferred stock, shares authorized (in shares)	50,000,000	50,000,000		50,000,000
Common stock issued in connection with stock options exercised (in shares)		8,759
Common stock issued through the dividend reinvestment plan (in shares)		2,721	2,777
Employee Stock Purchase Plans shares of common stock (in shares)		9,126
Number of shares of stock grants withheld (in shares)		73,652	93,181
Repurchases of shares (in shares)		786,797
Forward contract indexed to issuer's equity (in shares)				3,680,000
Forward contract indexed to issuer's equity, net proceeds		$ 808,606,000
Gross weighted average price (in dollars per share)				$ 226.52
Restricted Stock and Common Stock Converted from Performance Shares
Class of Stock [Line Items]
Equity instruments granted (in shares)		182,815	250,806
Restricted stock
Class of Stock [Line Items]
Equity instruments granted (in shares)		79,483	104,081
Stock issued during period, shares, share-based compensation, forfeited (in shares)		2,681	4,021
2020 Stock Repurchase Program
Class of Stock [Line Items]
Stock repurchase program, authorized amount	$ 500,000,000	$ 500,000,000
Average cost for shares Acquired (in dollars per share)	$ 192.99
Treasury stock value	$ 151,846,000
Stock repurchase program, remaining authorized amount	162,407,000	162,407,000
Continuous Equity Program CEP V
Class of Stock [Line Items]
Maximum value of shares of common stock that can be sold	$ 1,000,000,000	$ 1,000,000,000
Forward contract indexed to issuer's equity (in shares)				367,113
Forward contract indexed to issuer's equity, net proceeds				$ 80,687,000
Gross weighted average price (in dollars per share)				$ 223.27
Common stock sold under CEP V (in shares)	0	0
Common stock value, remaining to be authorized under continuous equity program	$ 623,997,000	$ 623,997,000

AVALONBAY COMMUNITIES INC 10-Q