XML 178 R162.htm IDEA: XBRL DOCUMENT v3.22.1
Retirement Benefit Plans - Effect on Present Value of Defined Benefit Obligation Due to a Reasonably Possible Change of the Significant Actuarial Assumptions (Detail) - TWD ($)
$ in Millions
Dec. 31, 2021
Dec. 31, 2020
Discount rates [Member]    
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]    
0.5% increase $ (1,073) $ (1,208)
0.5% decrease 1,139 1,284
Expected rates of salary increases [Member]    
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]    
0.5% increase 1,217 1,372
0.5% decrease $ (1,157) $ (1,303)