Financial Instruments - Summary of Carrying Amounts and Fair values of Group's Financial Instruments (Detail) - EUR (€) € in Thousands	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, Carrying amount	€ 15,635	€ 17,933	€ 34,395
IFRS 7 not applicable and IFRS 16 [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets and Financial liabilities	49,226	42,210
Cash and cash equivalents [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets and Financial liabilities	345,918	236,748
Short-Term Deposits [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets and Financial liabilities	123,419	367,704
Accounts receivables [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets and Financial liabilities	6,099	5,857
Other current/non-current assets [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets and Financial liabilities	30,422	20,496
Other current/non-current assets [Member] \| IFRS 7 not applicable and IFRS 16 [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets and Financial liabilities	28,034	19,252
Accounts payables [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets and Financial liabilities	18,832	20,693
Other current liabilities [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets and Financial liabilities	5,607	6,805
Other current liabilities [Member] \| IFRS 7 not applicable and IFRS 16 [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets and Financial liabilities	5,557	6,755
Liabilities for warrants [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets and Financial liabilities		1,730
Lease liabilities [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets and Financial liabilities	15,635	16,203
Lease liabilities [Member] \| IFRS 7 not applicable and IFRS 16 [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets and Financial liabilities	15,635	16,203
Financial liabilities at fair value through profit or loss, category [Member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, Carrying amount		1,730
Financial liabilities at fair value through profit or loss, category [Member] \| Liabilities for warrants [Member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, Carrying amount		1,730
Financial liabilities at amortised cost, category [Member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, Carrying amount	18,882	20,743
Financial liabilities at amortised cost, category [Member] \| Accounts payables [Member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, Carrying amount	18,832	20,693
Financial liabilities at amortised cost, category [Member] \| Other current liabilities [Member]
Disclosure of detailed information about financial instruments [line items]
Financial liabilities, Carrying amount	50	50
Financial assets at amortised cost, category [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets, Carrying amount	477,824	611,553
Financial assets at amortised cost, category [Member] \| Cash and cash equivalents [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets, Carrying amount	345,918	236,748
Financial assets at amortised cost, category [Member] \| Short-Term Deposits [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets, Carrying amount	123,419	367,704
Financial assets at amortised cost, category [Member] \| Accounts receivables [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets, Carrying amount	6,099	5,857
Financial assets at amortised cost, category [Member] \| Other current/non-current assets [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets, Carrying amount	€ 2,388	€ 1,244