v3.26.1
Cover - shares
 6 Months Ended
Jun. 30, 2026
Jul. 30, 2026
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Transition Report false  
Entity File Number 001-39299  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 86-1849232  
Entity Address, Address Line One 510 Lake Cook Road,  
Entity Address, Address Line Two Suite 400  
Entity Address, City or Town Deerfield  
Entity Address, State or Province IL  
Entity Address, Postal Zip Code 60015  
City Area Code (224)  
Local Phone Number 737-7000  
Title of 12(b) Security Class A Common Stock, par value $0.0001 per share  
Trading Symbol ALIT  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Amendment Flag false  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Entity Central Index Key 0001809104  
Current Fiscal Year End Date --12-31  
Entity Registrant Name Alight, Inc. / Delaware  
Former Address    
Document Information [Line Items]    
Entity Address, Address Line One 320 South Canal Street  
Entity Address, Address Line Two 50th Floor  
Entity Address, Address Line Three Suite 5000  
Entity Address, City or Town Chicago  
Entity Address, State or Province IL  
Entity Address, Postal Zip Code 60606  
Class A Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   26,419,410
Class B-1 Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   247,733
Class B-2 Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   247,733
Class V Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   24,217