Share-based Payment Arrangements - Summary of ASE Inc. Option Plans Outstanding Share Options (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
ASE Inc. option plans [member] \| Fifth share options exercise price [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Range of Exercise Price Per Share		$ 73
Remaining Contractual Life (Years)		8 months 12 days
The Company Option Plans [member] \| First share options exercise price [member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Range of Exercise Price Per Share	$ 41.1	$ 42.7
Remaining Contractual Life (Years)	2 years 10 months 24 days	3 years 10 months 24 days
The Company Option Plans [member] \| Second share options exercise price [Member]
Disclosure of terms and conditions of share-based payment arrangement [Line Items]
Range of Exercise Price Per Share	$ 99.7	$ 103.5
Remaining Contractual Life (Years)	7 years 7 months 6 days	8 years 7 months 6 days