v3.26.3
Earnings per Share - Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Dec. 31, 2024
Numerator (in thousands)            
Net income (loss) $ (5,019) $ 9,768 $ (1,144) $ 15,646    
Less: Net income (loss) attributable to non-controlling interests (9,995) 819 (9,568) 585    
Net income (loss) attributable to HMH Holding Inc. $ 4,976 $ 8,949 $ 8,424 $ 15,061    
Denominator (actual shares)            
Weighted-average shares of common stock for HMH and HMH B.V. outstanding—basic (in shares) 11,662 69,355 5,863 69,355    
Effect of dilutive securities (in shares) 309 0 825 0    
Weighted-average shares of Class A Common stock outstanding—diluted (in shares) 11,971 69,355 6,688 69,355    
Net income (loss) per share of common stock (actual)—Basic (in dollars per share) $ 0.43 $ 0.13 $ 1.44 $ 0.22    
Net income (loss) per share of Class A common stock (actual) — Diluted (in dollars per share) $ 0.42 $ 0.13 $ 1.26 $ 0.22    
HMH Holding BV And Subsidiaries [Member]            
Numerator (in thousands)            
Net income (loss)     $ (1,144) $ 15,646 $ 46,123 $ 51,956
Less: Net income (loss) attributable to non-controlling interests         669 738
Net income (loss) attributable to HMH Holding Inc.         $ 45,454 $ 51,218
Denominator (actual shares)            
Weighted-average shares of common stock for HMH and HMH B.V. outstanding—basic (in shares)         200 200
Weighted-average shares of Class A Common stock outstanding—diluted (in shares)         200 200
Net income (loss) per share of common stock (actual)—Basic (in dollars per share)         $ 227,270 $ 256,090
Net income (loss) per share of Class A common stock (actual) — Diluted (in dollars per share)         $ 227,270 $ 256,090