Marketable Securities - Summary of Marketable Securities (Detail) - EUR (€) € in Thousands | Sep. 30, 2021 | Dec. 31, 2020 |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Non-current financial assets available-for-sale | € 71,614 | € 115,280 |
Current financial assets available-for-sale | 165,347 | 134,278 |
Financial assets at amortised cost, class [member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets available-for-sale | 236,961 | 249,558 |
Non-current financial assets available-for-sale | 71,614 | 115,280 |
Current financial assets available-for-sale | 165,347 | 134,278 |
Financial assets | 236,961 | 249,558 |
Financial assets at amortised cost, class [member] | Prime [member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 6,529 | 7,716 |
Financial assets at amortised cost, class [member] | High grade [member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 116,055 | 142,339 |
Financial assets at amortised cost, class [member] | Upper Medium Grade [member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 112,270 | 99,503 |
Financial assets at amortised cost, class [member] | Lower Medium Grade [member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 2,107 | 0 |
Financial assets at amortised cost, class [member] | Fixed interest rate [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 220,163 | 175,757 |
Financial assets at amortised cost, class [member] | Floating interest rate [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 14,640 | 16,975 |
Financial assets at amortised cost, class [member] | Zero Coupon [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 2,158 | 56,826 |
Financial assets at amortised cost, class [member] | US Treasury bills [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets available-for-sale | 0 | 46,243 |
Financial assets at amortised cost, class [member] | US Government bonds [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets available-for-sale | 80,044 | 62,088 |
Financial assets at amortised cost, class [member] | Commercial papers [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets available-for-sale | 2,158 | 10,583 |
Financial assets at amortised cost, class [member] | Corporate bonds [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets available-for-sale | 136,204 | 121,282 |
Financial assets at amortised cost, class [member] | Agency bonds [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets available-for-sale | 18,555 | 9,362 |
Financial assets at fair value, class [member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets available-for-sale | 236,898 | 249,530 |
Non-current financial assets available-for-sale | 71,580 | 115,277 |
Current financial assets available-for-sale | 165,318 | 134,253 |
Financial assets | 236,898 | 249,530 |
Financial assets at fair value, class [member] | Prime [member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 6,529 | 7,714 |
Financial assets at fair value, class [member] | High grade [member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 116,057 | 142,352 |
Financial assets at fair value, class [member] | Upper Medium Grade [member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 112,206 | 99,464 |
Financial assets at fair value, class [member] | Lower Medium Grade [member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 2,106 | 0 |
Financial assets at fair value, class [member] | Fixed interest rate [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 220,100 | 175,732 |
Financial assets at fair value, class [member] | Floating interest rate [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 14,640 | 16,972 |
Financial assets at fair value, class [member] | Zero Coupon [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets | 2,158 | 56,826 |
Financial assets at fair value, class [member] | US Treasury bills [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets available-for-sale | 0 | 46,245 |
Financial assets at fair value, class [member] | US Government bonds [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets available-for-sale | 80,056 | 62,101 |
Financial assets at fair value, class [member] | Commercial papers [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets available-for-sale | 2,158 | 10,581 |
Financial assets at fair value, class [member] | Corporate bonds [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets available-for-sale | 136,128 | 121,234 |
Financial assets at fair value, class [member] | Agency bonds [Member] | | |
Disclosure Detailed Information About Marketable Securities [Line Items] | | |
Financial assets available-for-sale | € 18,556 | € 9,369 |