Share-based compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| 2023 Long-Term Incentive Plan [Member] | ||||
| Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] | ||||
| Share-based compensation arrangement by share-based payment award, description | In October 2023, the Company adopted the Group Long-Term Incentive Plan (“2023 LTIP”) to provide a select group of managers the opportunity to participate in the Company’s value creation. Awards granted under the 2023 LTIP are subject to both performance-vesting and market-vesting conditions and provide for cash settlement upon the occurrence of certain exit events or a change in control (“Exit”). | |||
| Share-based payment arrangement, expense | $ 61.5 | |||
| Share-based payment arrangement, noncash expense | $ 0.0 | $ 0.0 | $ 0.0 | $ 0.0 |
| 2026 Incentive Award Plan [Member] | ||||
| Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] | ||||
| Share-based compensation arrangement by share-based payment award, description | In connection with the Company’s IPO, the Board of Directors adopted the INNIO N.V. 2026 Incentive Award Plan (the “2026 Plan”), which became effective in June 2026. The 2026 Plan provides for the grant of equity-based awards to employees, directors and other eligible service providers, including stock options, restricted share units (“RSUs”), restricted shares, share appreciation rights, performance awards and other share-based awards. The Company registered shares available for issuance under the 2026 Plan on a Form S-8 filed with the SEC on June 5, 2026. | |||
| Share-based payment arrangement, expense | 1.1 | $ 1.1 | ||
| 2026 Incentive Award Plan [Member] | Restricted Stock Units (RSUs) [Member] | ||||
| Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] | ||||
| Share-based payment arrangement, nonvested award, cost not yet recognized, amount | $ 54.3 | $ 54.3 | ||
| Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period | 1,499,879 | |||
| Share-based compensation arrangement by share-based payment award, equity instruments other than options, grants in period, weighted average grant date fair value | $ 32.53 | |||
| Share-based compensation arrangement by share-based payment award, equity instruments other than options, vested in period | 202,221 | |||