Financial Assets at Fair Value Through Other Comprehensive Income - Summary of Investments in Equity Instruments at Fair Value Through Other Comprehensive Income (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2025 TWD ($)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 TWD ($)
Disclosure of fair value of investments in equity instruments designated at fair value through other comprehensive income [line items]
Investments in equity instruments at FVTOCI	$ 12,607,114	$ 401,885	$ 12,933,733
Unquoted ordinary shares [member]
Disclosure of fair value of investments in equity instruments designated at fair value through other comprehensive income [line items]
Investments in equity instruments at FVTOCI	12,546,772	399,961	12,846,151
Taiwan Innovation Board (TIB) quoted ordinary shares [member]
Disclosure of fair value of investments in equity instruments designated at fair value through other comprehensive income [line items]
Investments in equity instruments at FVTOCI	47,934	1,528	72,774
Unquoted preferred shares [member]
Disclosure of fair value of investments in equity instruments designated at fair value through other comprehensive income [line items]
Investments in equity instruments at FVTOCI	$ 12,408	$ 396	$ 14,808

Financial Assets at Fair Value Through Other Comprehensive Income - Summary of Investments in Equity Instruments at Fair Value Through Other Comprehensive Income (Detail)
$ in Thousands, $ in Thousands

Dec. 31, 2025

TWD ($)

Dec. 31, 2025

USD ($)

Dec. 31, 2024

TWD ($)

Disclosure of fair value of investments in equity instruments designated at fair value through other comprehensive income [line items]

Investments in equity instruments at FVTOCI

$ 12,607,114

$ 401,885

$ 12,933,733

Unquoted ordinary shares [member]