v3.26.3
Segment Information - Reconciliation of Segment Performance (Details) - USD ($)
 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
Segment Reporting [Line Items]            
Revenue from external customers $ 170,822,000 $ 203,457,000 $ 342,143,000 $ 401,887,000    
Cost of sales (109,524,000) (151,545,000) (226,157,000) (293,428,000)    
Selling, general and administrative expenses (60,354,000) (29,441,000) (95,465,000) (65,679,000)    
Research and development expenses (771,000) (649,000) (1,185,000) (1,680,000)    
Restructuring and other expenses (5,004,000) (1,072,000) (5,004,000) (4,343,000)    
Operating Income (Loss), Adjusted (1,881,000) 23,369,000 20,531,000 41,127,000    
Total segment operating income (loss) (1,881,000) 23,369,000 20,531,000 41,127,000    
Unallocated corporate costs (2,950,000) (2,619,000) (6,199,000) (4,370,000)    
Foreign currency gain (loss) (591,000) 2,948,000 (2,819,000) 6,941,000    
Other non-operating income (loss) (158,000) 334,000 (413,000) 647,000    
Interest expense (3,945,000) (9,106,000) (10,898,000) (18,285,000) $ (43,352,000) $ (37,255,000)
Income (loss) before income taxes (9,525,000) 14,926,000 202,000 26,060,000    
HMH Holding BV And Subsidiaries [Member]            
Segment Reporting [Line Items]            
Revenue from external customers         821,754,000 843,363,000 [1]
Cost of sales         (576,024,000) (571,173,000)
Selling, general and administrative expenses         (130,397,000) (146,810,000)
Research and development expenses         (2,813,000) (7,067,000)
Restructuring and other expenses         (4,631,000) 301,000
Operating Income (Loss), Adjusted         118,782,000 127,556,000
Total segment operating income (loss)         118,782,000 127,556,000
Unallocated corporate costs [2]         (10,893,000) (8,942,000)
Foreign currency gain (loss)         6,790,000 (5,293,000)
Other non-operating income (loss)         1,263,000 423,000
Interest expense         (43,352,000) (37,255)
Income (loss) before income taxes       72,590,000 72,590,000 76,489,000
ESS            
Segment Reporting [Line Items]            
Revenue from external customers 97,660,000 125,547,000 198,350,000 233,088,000    
Cost of sales (64,585,000) (94,696,000) (132,845,000) (170,410,000)    
Selling, general and administrative expenses (29,868,000) (18,166,000) (45,376,000) (38,064,000)    
Research and development expenses (442,000) (721,000) (685,000) (1,235,000)    
Restructuring and other expenses (261,000) (1,072,000) (261,000) (3,951,000)    
Operating Income (Loss), Adjusted 2,504,000 10,892,000 19,183,000 19,428,000    
Total segment operating income (loss) 2,504,000 10,892,000 19,183,000 19,428,000    
ESS | HMH Holding BV And Subsidiaries [Member]            
Segment Reporting [Line Items]            
Revenue from external customers [1]         438,553,000 443,189,000
Cost of sales         (303,314,000) (313,838,000)
Selling, general and administrative expenses [3]         (71,121,000) (72,015,000)
Research and development expenses         (2,165,000) (2,268,000)
Restructuring and other expenses [4]         (4,239,000) 301,000
Depreciation, Depletion and Amortization, Nonproduction [3]         (10,218,000) (9,236,000)
Operating Income (Loss), Adjusted         47,496,000 46,133,000
Total segment operating income (loss)         47,496,000 46,133,000
PCS            
Segment Reporting [Line Items]            
Revenue from external customers 73,162,000 77,910,000 143,793,000 168,799,000    
Cost of sales (44,939,000) (56,849,000) (93,312,000) (123,018,000)    
Selling, general and administrative expenses (27,536,000) (8,656,000) (43,890,000) (23,245,000)    
Research and development expenses (329,000) 72,000 (500,000) (445,000)    
Restructuring and other expenses (4,743,000) 0 (4,743,000) (392,000)    
Operating Income (Loss), Adjusted (4,385,000) 12,477,000 1,348,000 21,699,000    
Total segment operating income (loss) $ (4,385,000) $ 12,477,000 $ 1,348,000 $ 21,699,000    
PCS | HMH Holding BV And Subsidiaries [Member]            
Segment Reporting [Line Items]            
Revenue from external customers [1]         383,201,000 400,174,000
Cost of sales         (237,721,000) (223,169,000)
Selling, general and administrative expenses [3]         (46,142,000) (63,355,000)
Research and development expenses         (648,000) (4,799,000)
Restructuring and other expenses [4]         (392,000) 0
Depreciation, Depletion and Amortization, Nonproduction [3]         (27,012,000) (27,428,000)
Operating Income (Loss), Adjusted         71,286,000 81,423,000
Total segment operating income (loss)         $ 71,286,000 $ 81,423,000
[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] Unallocated corporate costs include certain corporate stewardship costs that are not allocable to the segments, consisting of centralized finance costs of $8.1 million and $7.0 million for the years ended December 31, 2025 and 2024, respectively, and other corporate expenses of $2.7 million and $1.9 million for the years ended December 31, 2025 and 2024, respectively.
[3] Depreciation and amortization expense is included in the consolidated statements of income within cost of sales and selling, general and administrative expenses.
[4] Restructuring and other expenses consist of severance costs primarily related to workforce reductions and reorganization within ESS and impairment of right-of-use assets.