Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2022	Aug. 03, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2022
Entity Registrant Name	LifeStance Health Group, Inc.
Entity Central Index Key	0001845257
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Shell Company	false
Document Quarterly Report	true
Document Transition Report	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Trading Symbol	LFST
Title of 12(b) Security	Common Stock, par value $0.01 per share
Security Exchange Name	NASDAQ
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		376,181,577
Entity File Number	001-40478
Entity Tax Identification Number	86-1832801
Entity Address, Address Line Two	Suite 6000
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	4800 N. Scottsdale Road
Entity Address, City or Town	Scottsdale
Entity Address, State or Province	AZ
Entity Address, Postal Zip Code	85251
City Area Code	602
Local Phone Number	767-2100