Retirement Benefit Plans - Summary of Sensitivity Analysis on Defined Obligations (Detail) $ in Thousands, $ in Thousands |
Dec. 31, 2025
TWD ($)
|
Dec. 31, 2025
USD ($)
|
Dec. 31, 2024
TWD ($)
|
|---|---|---|---|
| Actuarial assumption of discount rates [member] | |||
| Disclosure of sensitivity analysis for actuarial assumptions [line items] | |||
| Change in defined obligation due to increase in actuarial assumption | $ (739,299) | $ (23,567) | $ (641,795) |
| Change in defined obligation due to decrease in actuarial assumption | 794,986 | 25,342 | 687,690 |
| Actuarial assumption of expected rates of salary increases [member] | |||
| Disclosure of sensitivity analysis for actuarial assumptions [line items] | |||
| Change in defined obligation due to increase in actuarial assumption | 757,187 | 24,137 | 646,395 |
| Change in defined obligation due to decrease in actuarial assumption | $ 707,930 | $ 22,567 | $ 607,402 |