Revenue from Contracts with Customers - Contract Liabilities (Details) - USD ($) |
6 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Revenue from Contract with Customer [Abstract] | ||||
| Revenue recognized included in contract liabilities balance | $ 20,900,000 | $ 33,700,000 | ||
| Contract With Customer Asset And Liability [Line Items] | ||||
| Beginning balance | 35,249,000 | |||
| Additions | 88,333,000 | |||
| Revenue recognized | (80,802,000) | |||
| Ending balance | 42,780,000 | $ 35,249,000 | ||
| HMH Holding BV And Subsidiaries [Member] | ||||
| Revenue from Contract with Customer [Abstract] | ||||
| Revenue recognized included in contract liabilities balance | 50.7 | $ 71.3 | ||
| Contract With Customer Asset And Liability [Line Items] | ||||
| Beginning balance | $ 35,249,000 | $ 55,627,000 | 55,627,000 | 75,525,000 |
| Additions | 166,877,000 | 95,386,000 | ||
| Revenue recognized | (187,255,000) | (115,284,000) | ||
| Ending balance | $ 35,249,000 | $ 55,627,000 | ||