v3.26.1
Contents of Significant Accounts - Sensitivity Analysis (Detail) - TWD ($)
$ in Thousands
Dec. 31, 2025
Dec. 31, 2024
Discount rate [member]    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Decrease (increase) in defined benefit obligation due to 0.5% increase in actuarial assumptions $ 141,345 $ 154,095
Decrease (increase) in defined benefit obligation due to 0.5% decrease in actuarial assumptions $ (149,276) $ (163,088)
Percentage increase in actuarial assumptions 0.50% 0.50%
Percentage decrease in actuarial assumptions 0.50% 0.50%
Rate of future salary increase [member]    
Disclosure of sensitivity analysis for actuarial assumptions [line items]    
Decrease (increase) in defined benefit obligation due to 0.5% increase in actuarial assumptions $ (124,357) $ (137,421)
Decrease (increase) in defined benefit obligation due to 0.5% decrease in actuarial assumptions $ 119,311 $ 131,562
Percentage increase in actuarial assumptions 0.50% 0.50%
Percentage decrease in actuarial assumptions 0.50% 0.50%