Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2020	Jan. 29, 2021	Jun. 30, 2020
Cover [Abstract]
Title of 12(b) Security	Common Stock, par value $0.01 per share
Entity Incorporation, State or Country Code	MD
Entity Registrant Name	AVALONBAY COMMUNITIES, INC.
Entity Central Index Key	0000915912
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Document Type	10-K
Document Period End Date	Dec. 31, 2020
Entity File Number	1-12672
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		139,527,493
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Public Float			$ 21,698,072,550
Entity Tax Identification Number	77-0404318
Trading Symbol	AVB
Security Exchange Name	NYSE
Entity Address, Address Line One	4040 Wilson Blvd., Suite 1000
Entity Address, City or Town	Arlington
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	22203
City Area Code	703
Local Phone Number	329-6300
Documents Incorporated by Reference	Portions of AvalonBay Communities, Inc.'s Proxy Statement for the 2021 annual meeting of stockholders, a definitive copy of which will be filed with the SEC within 120 days after the year end of the year covered by this Form 10-K, are incorporated by reference herein as portions of Part III of this Form 10-K.
Document Annual Report	true
Document Transition Report	false
ICFR Auditor Attestation Flag	true