v3.26.3
Cover Page
 6 Months Ended
Jun. 30, 2026
Document Information [Line Items]  
Document Type S-1
Amendment Flag false
Entity Central Index Key 0002021880
Entity Registrant Name HMH Holding Inc.
Entity Incorporation, State or Country Code DE
Entity Primary SIC Number 3533
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
Entity Small Business false
Entity Filer Category Non-accelerated Filer
Entity Emerging Growth Company true
Entity Ex Transition Period false
Business Contact [Member]  
Document Information [Line Items]  
Contact Personnel Name Dwight W. Rettig
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