Contents of Significant Accounts - Major Categories of Plan Assets as a Percentage of Fair Value of the Total Plan Assets (Detail) |
Dec. 31, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Disclosure Of Fair Value Of Plan Assets [Abstract] | ||
| Cash | 16.00% | 21.00% |
| Equity instruments | 51.00% | 47.00% |
| Debt instruments | 22.00% | 21.00% |
| Others | 11.00% | 11.00% |