v3.26.3
Revenue from Contracts with Customers - Disaggregated Revenue (Details) - USD ($)
$ 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
Disaggregation of Revenue [Line Items]            
Total revenue $ 170,822 $ 203,457 $ 342,143 $ 401,887    
HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         $ 821,754 $ 843,363 [1]
Transferred overtime            
Disaggregation of Revenue [Line Items]            
Total revenue 104,968 128,987 196,115 249,526    
Transferred overtime | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         519,350 512,818
Transferred at point in time            
Disaggregation of Revenue [Line Items]            
Total revenue 65,854 74,470 146,028 152,361    
Transferred at point in time | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         302,404 330,545
ESS            
Disaggregation of Revenue [Line Items]            
Total revenue 97,660 125,547 198,350 233,088    
ESS | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue [1]         438,553 443,189
ESS | Transferred overtime            
Disaggregation of Revenue [Line Items]            
Total revenue 65,013 89,340 125,033 162,326    
ESS | Transferred overtime | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         300,400 299,928
ESS | Transferred at point in time            
Disaggregation of Revenue [Line Items]            
Total revenue 32,647 36,207 73,317 70,762    
ESS | Transferred at point in time | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         138,153 143,261
PCS            
Disaggregation of Revenue [Line Items]            
Total revenue 73,162 77,910 143,793 168,799    
PCS | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue [1]         383,201 400,174
PCS | Transferred overtime            
Disaggregation of Revenue [Line Items]            
Total revenue 39,955 39,647 71,082 87,200    
PCS | Transferred overtime | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         218,950 212,890
PCS | Transferred at point in time            
Disaggregation of Revenue [Line Items]            
Total revenue 33,207 38,263 72,711 81,599    
PCS | Transferred at point in time | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         164,251 187,284
Project and other manufacturing contracts revenue            
Disaggregation of Revenue [Line Items]            
Total revenue 10,093 33,139 22,385 57,756    
Project and other manufacturing contracts revenue | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         92,436 70,462
Project and other manufacturing contracts revenue | ESS            
Disaggregation of Revenue [Line Items]            
Total revenue 5,395 29,102 14,416 48,276    
Project and other manufacturing contracts revenue | ESS | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         61,130 33,552
Project and other manufacturing contracts revenue | PCS            
Disaggregation of Revenue [Line Items]            
Total revenue 4,698 4,037 7,969 9,480    
Project and other manufacturing contracts revenue | PCS | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         31,306 36,910
Sale of products            
Disaggregation of Revenue [Line Items]            
Total revenue 10,494 25,835 30,995 55,966    
Sale of products | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         121,553 158,674
Sale of products | ESS            
Disaggregation of Revenue [Line Items]            
Total revenue 7,508 12,986 15,651 29,923    
Sale of products | ESS | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         64,558 108,610
Sale of products | PCS            
Disaggregation of Revenue [Line Items]            
Total revenue 2,986 12,849 15,344 26,043    
Sale of products | PCS | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         56,995 50,064
Product revenue            
Disaggregation of Revenue [Line Items]            
Total revenue 20,587 58,974 53,380 113,722    
Product revenue | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue [2]         213,989 229,136
Product revenue | ESS            
Disaggregation of Revenue [Line Items]            
Total revenue 12,903 42,088 30,067 78,199    
Product revenue | ESS | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue [2]         125,688 142,162
Product revenue | PCS            
Disaggregation of Revenue [Line Items]            
Total revenue 7,684 16,886 23,313 35,523    
Product revenue | PCS | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue [2]         88,301 86,974
Service revenue            
Disaggregation of Revenue [Line Items]            
Total revenue 89,072 92,332 161,081 175,840    
Service revenue | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         383,385 366,202
Service revenue | ESS            
Disaggregation of Revenue [Line Items]            
Total revenue 53,815 56,722 97,968 98,120    
Service revenue | ESS | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         195,741 190,222
Service revenue | PCS            
Disaggregation of Revenue [Line Items]            
Total revenue 35,257 35,610 63,113 77,720    
Service revenue | PCS | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         187,644 175,980
Spare parts revenue            
Disaggregation of Revenue [Line Items]            
Total revenue 61,163 52,151 127,682 112,325    
Spare parts revenue | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         224,380 248,025
Spare parts revenue | ESS            
Disaggregation of Revenue [Line Items]            
Total revenue 30,942 26,737 70,315 56,769    
Spare parts revenue | ESS | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         117,124 110,805
Spare parts revenue | PCS            
Disaggregation of Revenue [Line Items]            
Total revenue $ 30,221 $ 25,414 $ 57,367 $ 55,556    
Spare parts revenue | PCS | HMH Holding BV And Subsidiaries [Member]            
Disaggregation of Revenue [Line Items]            
Total revenue         $ 107,256 $ 137,220
[1] As the CODM does not regularly review intersegment revenue, it is excluded from the determination of total segment operating income. The CODM uses revenue from external customers to assess performance and allocate resources.
[2] Product revenue includes related party revenue.