v3.26.1
Financial Instruments - Summary Of Significant Unobservable Inputs Used In Level 3 Fair Value Measurements (Detail)
€ in Millions
 12 Months Ended
Dec. 31, 2025
EUR (€)
Unlisted Equity Securities [Member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Fair Value € 10.0
Unlisted Equity Securities [Member] | Highyield corporate bond rate [Member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Relationship Of Unobservable Inputs To Fair Value The higher the discount rate, the lower the fair value
Unlisted Equity Securities [Member] | Highyield corporate bond rate [Member] | Bottom of range [member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Range Of Inputs (Probability- Weighted Average) € 8.0
Unlisted Equity Securities [Member] | Highyield corporate bond rate [Member] | Weighted average [member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Range Of Inputs (Probability- Weighted Average) 9.6
Unlisted Equity Securities [Member] | Highyield corporate bond rate [Member] | Top of range [member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Range Of Inputs (Probability- Weighted Average) 10.0
Unlisted Equity Securities [Member] | Eurobond Government rate [Member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Fair Value 3.0
Unlisted Equity Securities [Member] | Eurobond Government rate [Member] | Bottom of range [member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Range Of Inputs (Probability- Weighted Average) 2.0
Unlisted Equity Securities [Member] | Eurobond Government rate [Member] | Weighted average [member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Range Of Inputs (Probability- Weighted Average) 2.2
Unlisted Equity Securities [Member] | Eurobond Government rate [Member] | Top of range [member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Range Of Inputs (Probability- Weighted Average) 3.0
Contingent Value Rights [Member] | Highyield corporate bond rate [Member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Fair Value € 4.0
Contingent Value Rights [Member] | Eurobond Government rate [Member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Relationship Of Unobservable Inputs To Fair Value The higher the discount rate, the lower the fair value
Contingent Value Rights [Member] | Discount rate, measurement input [member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Fair Value € 755.0
Relationship Of Unobservable Inputs To Fair Value The higher the discount rate, the lower the fair value
Contingent Value Rights [Member] | Discount rate, measurement input [member] | Bottom of range [member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Range Of Inputs (Probability- Weighted Average) € 8.0
Contingent Value Rights [Member] | Discount rate, measurement input [member] | Weighted average [member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Range Of Inputs (Probability- Weighted Average) 8.5
Contingent Value Rights [Member] | Discount rate, measurement input [member] | Top of range [member]  
Disclosure of sensitivity analysis of fair value measurement to changes in unobservable inputs, entity's own equity instruments [line items]  
Range Of Inputs (Probability- Weighted Average) € 9.0