XML 100 R82.htm IDEA: XBRL DOCUMENT v3.22.1
Hedging Financial Instruments - Summary of Information Related to Hedges of Interest Rate Risk (Detail)
$ in Millions, $ in Millions
 12 Months Ended
Dec. 31, 2021
TWD ($)
Dec. 31, 2021
USD ($)
Dec. 31, 2020
TWD ($)
Dec. 31, 2019
TWD ($)
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Disclosure of detailed information about financial instruments [line items]            
Increase (Decrease) in Value Used for Calculating Hedge Ineffectiveness $ (41.4) $ (1.5) $ 24.1 $ (109.6)    
Fair value hedges [member]            
Disclosure of detailed information about financial instruments [line items]            
Increase (Decrease) in Value Used for Calculating Hedge Ineffectiveness       13.1    
US treasury bonds interest rate futures contracts [member]            
Disclosure of detailed information about financial instruments [line items]            
Contract Amount         $ 53.9 $ 88.7
Maturity March 2022 March 2022 March 2021      
US treasury bonds interest rate futures contracts [member] | Fair value hedges [member]            
Disclosure of detailed information about financial instruments [line items]            
Increase (Decrease) in Value Used for Calculating Hedge Ineffectiveness $ 148.8   $ (353.6) (164.7)    
FVTOCI [member]            
Disclosure of detailed information about financial instruments [line items]            
Asset Carrying Amount 4,079.3   6,198.7      
Asset Accumulated Amount of Fair Value Hedge Adjustments 9.6   1.1      
FVTOCI [member] | Fair value hedges [member]            
Disclosure of detailed information about financial instruments [line items]            
Increase (Decrease) in Value Used for Calculating Hedge Ineffectiveness $ (148.8)   $ 353.6 $ 177.8