Earnings and Loss per Share - Summary of Earnings and Loss per Share (Detail) - EUR (€) € / shares in Units, € in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Numerator:
Net loss	€ (62,492)	€ (70,348)	€ (120,306)	€ (110,204)
Adjustments of loss	0	0	0	0
Net loss available to common shareholders	€ (62,492)	€ (70,348)	€ (120,306)	€ (110,204)
Denominator:
Weighted average shares outstanding - Basic	136,680,065	121,552,940	135,673,812	121,551,570
Effect of potentially dilutive warrants / shares option	0	0	0	0
Weighted average shares outstanding - Diluted	136,680,065	121,552,940	135,673,812	121,551,570
Loss per share - Basic	€ (0.46)	€ (0.58)	€ (0.89)	€ (0.91)
Loss per share - Diluted	€ (0.46)	€ (0.58)	€ (0.89)	€ (0.91)

The weighted average number of ordinary shares outstanding plus the weighted average number of ordinary shares that would be issued on the conversion of all the dilutive potential ordinary shares into ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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