v3.26.1
Financial Risk and Fair Value Disclosures - Reconciliation for Fair Value Measurement in Level 3 Fair Value Hierarchy (Detail)
$ in Thousands, $ in Thousands
 12 Months Ended
Dec. 31, 2025
TWD ($)
Dec. 31, 2025
USD ($)
Dec. 31, 2024
TWD ($)
Disclosure of fair value measurement of assets [line items]      
Beginning balance $ 560,168,955    
Ending balance 567,274,863 $ 18,083,355 $ 560,168,955
Level 3 [member] | Financial assets at fair value through profit or loss [member]      
Disclosure of fair value measurement of assets [line items]      
Beginning balance 12,128,789   10,251,085
Recognized in profit (loss) (307,161)   203,424
Recognized in other comprehensive income (loss) 0   0
Acquisition 995,834   2,329,820
Disposal (551,700)   (566,983)
Return of capital (19,777)   (12,488)
Transfer out of Level 3 (194,460)   (377,121)
Exchange effect (226,459)   301,052
Ending balance 11,825,066   12,128,789
Level 3 [member] | Financial assets at fair value through profit or loss [member] | Common stock [member]      
Disclosure of fair value measurement of assets [line items]      
Beginning balance 3,008,183   3,036,255
Recognized in profit (loss) (38,312)   (119,584)
Recognized in other comprehensive income (loss) 0   0
Acquisition 264,125   505,538
Disposal (10,142)   (78,234)
Return of capital 0   (83)
Transfer out of Level 3 (194,460)   (377,121)
Exchange effect (29,257)   41,412
Ending balance 3,000,137   3,008,183
Level 3 [member] | Financial assets at fair value through profit or loss [member] | Preferred stocks [member]      
Disclosure of fair value measurement of assets [line items]      
Beginning balance 3,403,933   2,786,634
Recognized in profit (loss) 298,725   187,131
Recognized in other comprehensive income (loss) 0   0
Acquisition 281,776   639,779
Disposal (66,319)   (311,066)
Return of capital 0   0
Transfer out of Level 3 0   0
Exchange effect (77,041)   101,455
Ending balance 3,841,074   3,403,933
Level 3 [member] | Financial assets at fair value through profit or loss [member] | Funds [member]      
Disclosure of fair value measurement of assets [line items]      
Beginning balance 5,596,447   4,274,896
Recognized in profit (loss) (565,008)   128,617
Recognized in other comprehensive income (loss) 0   0
Acquisition 292,459   1,133,312
Disposal (372,135)   (81,371)
Return of capital (19,777)   (12,405)
Transfer out of Level 3 0   0
Exchange effect (119,443)   153,398
Ending balance 4,812,543   5,596,447
Level 3 [member] | Financial assets at fair value through profit or loss [member] | Convertible bonds [member]      
Disclosure of fair value measurement of assets [line items]      
Beginning balance 54,766   0
Recognized in profit (loss) 194   3,120
Recognized in other comprehensive income (loss) 0   0
Acquisition 147,571   51,191
Disposal (103,104)   0
Return of capital 0   0
Transfer out of Level 3 0   0
Exchange effect (775)   455
Ending balance 98,652   54,766
Level 3 [member] | Financial assets at fair value through profit or loss [member] | Others [Member]      
Disclosure of fair value measurement of assets [line items]      
Beginning balance 65,460   153,300
Recognized in profit (loss) (2,760)   4,140
Recognized in other comprehensive income (loss) 0   0
Acquisition 9,903   0
Disposal 0   (96,312)
Return of capital 0   0
Transfer out of Level 3 0   0
Exchange effect 57   4,332
Ending balance 72,660   65,460
Level 3 [member] | Financial assets at fair value through other comprehensive income [member]      
Disclosure of fair value measurement of assets [line items]      
Beginning balance 3,436,398   3,237,388
Recognized in profit (loss) 0   0
Recognized in other comprehensive income (loss) (272,193)   134,316
Acquisition 150,000   64,694
Disposal 0   0
Return of capital (160,659)   0
Transfer out of Level 3 0   0
Exchange effect 0   0
Ending balance 3,153,546   3,436,398
Level 3 [member] | Financial assets at fair value through other comprehensive income [member] | Common stock [member]      
Disclosure of fair value measurement of assets [line items]      
Beginning balance 3,231,518   3,062,325
Recognized in profit (loss) 0   0
Recognized in other comprehensive income (loss) (270,121)   104,499
Acquisition 150,000   64,694
Disposal 0   0
Return of capital (160,659)   0
Transfer out of Level 3 0   0
Exchange effect 0   0
Ending balance 2,950,738   3,231,518
Level 3 [member] | Financial assets at fair value through other comprehensive income [member] | Preferred stocks [member]      
Disclosure of fair value measurement of assets [line items]      
Beginning balance 204,880   175,063
Recognized in profit (loss) 0   0
Recognized in other comprehensive income (loss) (2,072)   29,817
Acquisition 0   0
Disposal 0   0
Return of capital 0   0
Transfer out of Level 3 0   0
Exchange effect 0   0
Ending balance $ 202,808   $ 204,880