v3.26.1
Contents of Significant Accounts - Reconciliation of Liabilities Arising from Financing Activities (Detail) - TWD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Short-term loans [member]      
Disclosure of reconciliation of liabilities arising from financing activities [line items]      
Beginning balance $ 8,515,000 $ 13,530,000 $ 0
Cash Flows (106,531) (5,015,000) 13,530,000
Non-cash changes,Foreign exchange 303 0 0
Non-cash changes,Others [1] 0 0 0
Ending Balance 8,408,772 8,515,000 13,530,000
Bonds payable (current portion included) [member]      
Disclosure of reconciliation of liabilities arising from financing activities [line items]      
Beginning balance 30,051,568 38,359,352 28,184,687
Cash Flows 19,984,120 (8,500,465) 9,989,245
Non-cash changes,Foreign exchange 0 0  
Non-cash changes,Others [1] 192,617 192,681 185,420
Ending Balance 50,228,305 30,051,568 38,359,352
Long-term loans (current portion included) [member]      
Disclosure of reconciliation of liabilities arising from financing activities [line items]      
Beginning balance 36,476,909 22,883,344 19,279,342
Cash Flows (21,689,386) 13,178,434 3,857,704
Non-cash changes,Foreign exchange (455,733) 415,131 (253,702)
Non-cash changes,Others [1] 0 0 0
Ending Balance 14,331,790 36,476,909 22,883,344
Lease liabilities [member]      
Disclosure of reconciliation of liabilities arising from financing activities [line items]      
Beginning balance 6,419,016 5,393,187 5,737,095
Cash Flows (849,810) (731,138) (666,439)
Non-cash changes,Foreign exchange (8,014) 92,617 (24,106)
Non-cash changes,Others [1],[2] 439,654 1,664,350 346,637
Ending Balance 6,000,846 6,419,016 5,393,187
Guarantee deposits (current portion included) [member]      
Disclosure of reconciliation of liabilities arising from financing activities [line items]      
Beginning balance 42,874,494 [3] 41,599,386 [3] 30,757,001
Cash Flows (780,352) (572,321) 10,423,345
Non-cash changes,Foreign exchange (1,226,308) 1,847,429 419,040
Non-cash changes,Others [1] 23 0 0
Ending Balance [3] $ 40,867,857 42,874,494 41,599,386
Other financial liabilities [member]      
Disclosure of reconciliation of liabilities arising from financing activities [line items]      
Beginning balance   $ 0 21,449,487
Cash Flows     (21,209,443)
Non-cash changes,Foreign exchange     (330,783)
Non-cash changes,Others [1]     90,739
Ending Balance     $ 0
[1] Other non-cash changes mainly consisted of discount amortization measured by the effective interest method.
[2] Mainly due to the addition to lease properties .
[3] Guarantee deposits mainly consisted of deposits of capacity reservation.