v3.26.1
Cover Page - shares
 6 Months Ended
Jun. 30, 2026
Jul. 31, 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 001-43221  
Entity Registrant Name HMH Holding Inc  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 99-2746883  
Entity Address, Address Line One 3300 North Sam Houston Parkway East  
Entity Address, City or Town Houston  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 77032  
City Area Code (281)  
Local Phone Number 449-2000  
Title of 12(b) Security Class A common stock, par value $0.01 per share  
Trading Symbol HMH  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Small Business false  
Entity Filer Category Non-accelerated Filer  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Entity Central Index Key 0002021880  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Current Fiscal Year End Date --12-31  
Amendment Flag false  
Class A Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   12,042,625
Class B Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   31,891,652