v3.26.1
Earnings per Share - Additional Information (Details) - shares
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2025
Jun. 30, 2026
Apr. 01, 2026
HMH Holding B.V. And Subsidiaries        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Common stock, shares outstanding (in shares)     63,783,304  
Class A Common Stock        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Common stock, shares outstanding (in shares)     12,042,625  
Shares issuable (in shares)     31,891,652  
Class A Common Stock | IPO        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Number of shares issued in 2026 that are excluded from calculation of basis and diluted EPS in 2025 11,200,000 11,200,000    
Issued upon completion of IPO and related effect of reorganization (in shares) 11,200,000 11,200,000    
Class A Common Stock | HMH Holding B.V. And Subsidiaries        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Common stock, shares outstanding (in shares)       100
Class B Common Stock        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Common stock, shares outstanding (in shares)     31,891,652  
Class B Common Stock | HMH Holding B.V. And Subsidiaries        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Common stock, shares outstanding (in shares)       100