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Trade Notes and Accounts Payable - Summary of Trade Notes and Accounts Payable (Detail)
$ in Millions, $ in Millions
Dec. 31, 2020
TWD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
TWD ($)
Trade And Other Current Payables [Abstract]      
Trade notes and accounts payable $ 15,591 $ 555 $ 15,312