v3.26.1
Income Tax - Summary of Movements of Deferred Tax Assets and Deferred Tax Liabilities (Detail)
$ in Thousands, $ in Thousands
 12 Months Ended
Dec. 31, 2025
TWD ($)
Dec. 31, 2025
USD ($)
Dec. 31, 2024
TWD ($)
Dec. 31, 2023
TWD ($)
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Recognized in Profit or Loss $ 2,256,972 $ 71,947 $ 1,692,905 $ 1,296,257
Recognized in Other Comprehensive Income (130,741) (4,168) (82,157) (270,410)
Recognized in Equity (252,723) (8,056) 0 0
Deferred tax assets [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 7,175,371 228,733 6,395,595 6,341,772
Acquisitions through Business Combinations 4,032 128 153,821 893
Recognized in Profit or Loss 40,297 1,285 882,998 (65,243)
Recognized in Other Comprehensive Income 270,298 8,617 (62,170) (4,844)
Exchange Differences 208,210 6,637 (194,873) 123,017
Balance at December 31 7,698,208 245,400 7,175,371 6,395,595
Deferred tax liabilities [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 6,850,104 218,365 7,703,646 8,585,132
Acquisitions through Business Combinations 15 1 92,842 109,945
Recognized in Profit or Loss (2,216,675) (70,663) (809,907) (1,361,500)
Recognized in Other Comprehensive Income 401,039 12,785 19,987 265,566
Recognized in Equity 252,723 8,056    
Exchange Differences 103,815 3,309 (156,464) 104,503
Balance at December 31 5,391,021 171,853 6,850,104 7,703,646
Property, plant and equipment [member] | Deferred tax assets [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 354,552 11,302 266,164 148,428
Acquisitions through Business Combinations     123,696  
Recognized in Profit or Loss 33,759 1,076 (36,352) 110,253
Exchange Differences 84,763 2,702 1,044 7,483
Balance at December 31 473,074 15,080 354,552 266,164
Property, plant and equipment [member] | Deferred tax liabilities [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 3,725,920 118,773 5,135,461 6,038,258
Acquisitions through Business Combinations     92,842 10,410
Recognized in Profit or Loss (1,231,017) (39,242) (1,573,888) (902,114)
Exchange Differences 70,869 2,259 71,505 (11,093)
Balance at December 31 2,565,772 81,790 3,725,920 5,135,461
Defined benefit obligation [member] | Deferred tax assets [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 664,946 21,197 819,307 862,434
Recognized in Profit or Loss (93,418) (2,978) (149,680) (68,968)
Recognized in Other Comprehensive Income 270,298 8,617 (62,170) (4,844)
Exchange Differences (74,127) (2,363) 57,489 30,685
Balance at December 31 767,699 24,473 664,946 819,307
Defined benefit obligation [member] | Deferred tax liabilities [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 18,287 583 54,634  
Recognized in Profit or Loss 1,617 51 (35,210) 27,031
Recognized in Other Comprehensive Income 20,409 651 14 (2,630)
Exchange Differences (30,042) (958) (1,151) 30,233
Balance at December 31 10,271 327 18,287 54,634
Mandatorily at fair value through profit or loss [member] | Deferred tax assets [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 163,885 5,224 251,890 207,794
Recognized in Profit or Loss (165,781) (5,284) (87,612) 43,792
Exchange Differences (282) (9) (393) 304
Balance at December 31 (2,178) (69) 163,885 251,890
Mandatorily at fair value through profit or loss [member] | Deferred tax liabilities [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 868,748 27,694 45,081 531,811
Recognized in Profit or Loss (309,275) (9,859) 823,904 (487,098)
Exchange Differences (606) (19) (237) 368
Balance at December 31 558,867 17,816 868,748 45,081
Other temporary differences [member] | Deferred tax assets [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 4,313,282 137,497 4,182,316 3,769,504
Acquisitions through Business Combinations     16,067 893
Recognized in Profit or Loss 52,135 1,662 347,938 316,527
Exchange Differences 149,599 4,769 (233,039) 95,392
Balance at December 31 4,515,016 143,928 4,313,282 4,182,316
Other temporary differences [member] | Deferred tax liabilities [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 2,237,149 71,315 2,468,470 2,015,063
Acquisitions through Business Combinations 15 1   99,535
Recognized in Profit or Loss (678,000) (21,613) (24,713) 681
Recognized in Other Comprehensive Income 380,630 12,134 19,973 268,196
Recognized in Equity 252,723 8,056    
Exchange Differences 63,594 2,027 (226,581) 84,995
Balance at December 31 2,256,111 71,920 2,237,149 2,468,470
Temporary differences [member] | Deferred tax assets [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 5,496,665 175,220 5,519,677 4,988,160
Acquisitions through Business Combinations     139,763 893
Recognized in Profit or Loss (173,305) (5,524) 74,294 401,604
Recognized in Other Comprehensive Income 270,298 8,617 (62,170) (4,844)
Exchange Differences 159,953 5,099 (174,899) 133,864
Balance at December 31 5,753,611 183,412 5,496,665 5,519,677
Unused tax losses [member] | Deferred tax assets [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 745,378 23,761 555,297 495,485
Acquisitions through Business Combinations 4,032 128 14,058  
Recognized in Profit or Loss (2,363) (75) 250,063 56,005
Exchange Differences (4,820) (154) (74,040) 3,807
Balance at December 31 742,227 23,660 745,378 555,297
Unused tax credits [member] | Deferred tax assets [member]        
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]        
Balance at January 1 933,328 29,752 320,621 858,127
Recognized in Profit or Loss 215,965 6,884 558,641 (522,852)
Exchange Differences 53,077 1,692 54,066 (14,654)
Balance at December 31 $ 1,202,370 $ 38,328 $ 933,328 $ 320,621