XML 184 R166.htm IDEA: XBRL DOCUMENT v3.8.0.1
Financial Instruments - Fair Value of Financial Instruments Not Measured at Fair Value but for which Fair Value is Disclosed (Detail) - TWD ($)
$ in Millions
Dec. 31, 2017
Dec. 31, 2016
Disclosure of detailed information about financial instruments [line items]    
Financial assets $ 804,091.0 $ 790,858.6
Financial liabilities 340,543.5 387,237.3
Not measured at fair value but for which the fair value is disclosed [member] | Financial liabilities at amortised cost [member] | Bonds payable including long-term liabilities-current portion) [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial liabilities 150,201.1 191,193.6
Financial liabilities 152,077.7 192,845.3
Not measured at fair value but for which the fair value is disclosed [member] | Financial liabilities at amortised cost [member] | Level 2 [member] | Bonds payable including long-term liabilities-current portion) [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial liabilities 152,077.7 192,845.3
Not measured at fair value but for which the fair value is disclosed [member] | Fair value [member] | Financial liabilities at amortised cost [member] | Bonds payable including long-term liabilities-current portion) [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial liabilities 152,077.7 192,845.3
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets 21,016.8 39,084.7
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Corporate bonds [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets 19,338.8 23,849.7
Financial assets 19,541.4 23,996.4
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Structured product [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets 1,482.9 1,609.9
Financial assets 1,475.4 1,609.7
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Commercial paper [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets   8,628.2
Financial assets   8,630.8
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Negotiable certificate of deposit [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets   4,829.9
Financial assets   4,847.8
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Level 2 [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets 21,016.8 39,084.7
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Level 2 [member] | Corporate bonds [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets 19,541.4 23,996.4
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Level 2 [member] | Structured product [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets 1,475.4 1,609.7
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Level 2 [member] | Commercial paper [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets   8,630.8
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Level 2 [member] | Negotiable certificate of deposit [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets   4,847.8
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Fair value [member] | Corporate bonds [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets 19,541.4 23,996.4
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Fair value [member] | Structured product [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets $ 1,475.4 1,609.7
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Fair value [member] | Commercial paper [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets   8,630.8
Not measured at fair value but for which the fair value is disclosed [member] | Held-to-maturity [Member] | Fair value [member] | Negotiable certificate of deposit [member]    
Disclosure of detailed information about financial instruments [line items]    
Financial assets   $ 4,847.8