v3.25.1
Document and Entity Information - shares
 3 Months Ended
Mar. 31, 2025
Apr. 30, 2025
Cover [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Mar. 31, 2025  
Entity Registrant Name LifeStance Health Group, Inc.  
Entity Central Index Key 0001845257  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Document Quarterly Report true  
Document Transition Report false  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q1  
Trading Symbol LFST  
Title of 12(b) Security Common Stock, par value $0.01 per share  
Security Exchange Name NASDAQ  
Entity Common Stock, Shares Outstanding   388,875,906
Entity File Number 001-40478  
Entity Tax Identification Number 86-1832801  
Entity Address, Address Line Two Suite 2500  
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