Equity - Summary of Shares Held By Subsidiaries (Detail) shares in Thousands, $ in Thousands, $ in Thousands	Dec. 31, 2024 TWD ($) shares	Dec. 31, 2024 USD ($) shares	Dec. 31, 2023 TWD ($) shares
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries (in thousands)	72,941	72,941	72,941
Shares Held By Subsidiaries, Value	$ 1,959,107	$ 59,747	$ 1,959,107
ASE [member]
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries (in thousands)	67,452	67,452	67,452
Shares Held By Subsidiaries, Value	$ 1,762,430	$ 53,749	$ 1,762,430
ASE Test, Inc. [member]
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries (in thousands)	5,489	5,489	5,489
Shares Held By Subsidiaries, Value	$ 196,677	$ 5,998	$ 196,677
Fair value [member]
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries, Value	11,816,524	360,370	9,847,103
Fair value [member] \| ASE [member]
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries, Value	10,927,243	333,249	9,106,036
Fair value [member] \| ASE Test, Inc. [member]
Disclosure of subsidiaries [Line Items]
Shares Held By Subsidiaries, Value	$ 889,281	$ 27,121	$ 741,067