Cover - shares	9 Months Ended
	Sep. 30, 2022	Oct. 28, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2022
Document Transition Report	false
Entity File Number	1-16817
Entity Registrant Name	ALERISLIFE INC.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	04-3516029
Entity Address, Address Line One	Two Newton Place, 255 Washington Street,
Entity Address, Address Line Two	Suite 230
Entity Address, City or Town	Newton
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02458
City Area Code	617
Local Phone Number	796-8387
Title of 12(b) Security	Common Stock
Trading Symbol	ALR
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		32,609,007
Entity Central Index Key	0001159281
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Amendment Flag	false
Current Fiscal Year End Date	--12-31