v3.26.1
Equity - Summary of Unrealized Gain (Loss) on Financial Assets at FVTOCI (Detail)
$ in Thousands, $ in Thousands
 12 Months Ended
Dec. 31, 2025
TWD ($)
Dec. 31, 2025
USD ($)
Dec. 31, 2024
TWD ($)
Dec. 31, 2023
TWD ($)
Financial assets at fair value through other comprehensive income [line items]        
Balance at January 1 $ 13,959,493      
Other comprehensive income (loss) for the year, net of income tax (3,617,203) $ (115,307) $ 13,638,305 $ 449,350
Ending balance 13,615,254 434,022 13,959,493  
Unrealized gain (loss) on financial assets at fair value through other comprehensive income [member]        
Financial assets at fair value through other comprehensive income [line items]        
Balance at January 1 3,730,559 118,921 3,549,648 1,275,505
Debt instruments (15,241) (486) (14,830) (22,599)
Equity instruments (612,141) (19,514) (18,871) (77,496)
Share from associates and joint ventures accounted for using the equity method 4,352,949 138,762 155,784 2,447,656
Other comprehensive income (loss) for the year, net of income tax 3,725,567 118,762 122,083 2,347,561
Cumulative unrealized loss of equity instruments transferred to retained earnings due to disposal 15,489 494 72,049 230,940
Cumulative unrealized gain transferred to retained earnings due to disposal of equity instruments in relation to associates and joint venture accounted for using the equity method (5)   (13,221) (304,358)
Ending balance $ 7,471,610 $ 238,177 $ 3,730,559 $ 3,549,648