Financial Instruments - Summary of Categories of Financial Instruments (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2018 USD ($)	Dec. 31, 2018 TWD ($)	Dec. 31, 2017 TWD ($)
Disclosure of detailed information about financial instruments [line items]
Financial assets designated as at FVTPL			$ 100,496
Held for trading			5,122,571
Mandatorily at FVTPL	$ 258,035	$ 7,898,458
Available-for-sale financial assets			1,212,165
Held for trading	1,197	36,655	677,430
Financial liabilities for hedging	127,397	3,899,634
Measured at amortized cost (Note 2)	9,344,520	286,035,732	139,561,999
Mandatorily at fair value through profit or loss [member]
Disclosure of detailed information about financial instruments [line items]
Available-for-sale financial assets			1,212,165
Loans and receivables			$ 103,973,567
Measured at amortized cost	4,569,314	139,866,736
Financial assets at fair value through other comprehensive income, category [member]
Disclosure of detailed information about financial instruments [line items]
Equity instruments	18,961	580,399
Debt instruments	$ 33,222	$ 1,016,924

Financial liabilities designated as hedging instruments at fair value through profit or loss

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The amount of current debt instruments issued. [Refer: Debt instruments issued]

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The amount of current financial assets measured at fair value through profit or loss classified as held for trading. [Refer: Financial assets at fair value through profit or loss, classified as held for trading]

+ References

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The amount of current financial assets measured at fair value through profit or loss that were designated as such upon initial recognition or subsequently. [Refer: Financial assets at fair value through profit or loss, designated upon initial recognition or subsequently]

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The amount of current financial assets mandatorily measured at fair value through profit or loss in accordance with IFRS 9. [Refer: Financial assets at fair value through profit or loss, mandatorily measured at fair value]

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The amount of current financial liabilities at fair value through profit or loss that meet the definition of held for trading. [Refer: Current financial liabilities at fair value through profit or loss]

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The amount of current investments in equity instruments that the entity has designated at fair value through other comprehensive income. [Refer: Investments in equity instruments designated at fair value through other comprehensive income]

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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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No definition available.

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The amount of financial assets at amortised cost. The amortised cost is the amount at which financial assets are measured at initial recognition minus principal repayments, plus or minus the cumulative amortisation using the effective interest method of any difference between that initial amount and the maturity amount, and adjusted for any impairment. [Refer: Financial assets]

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The amount of non-derivative financial assets that are designated as available for sale or are not classified as (a) loans and receivables; (b) held-to-maturity investments; or (c) financial assets at fair value through profit or loss. [Refer: Derivative financial assets; Financial assets at fair value through profit or loss; Held-to-maturity investments]

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The amount of financial liabilities at amortised cost. The amortised cost is the amount at which financial liabilities are measured at initial recognition minus principal repayments, plus or minus the cumulative amortisation using the effective interest method of any difference between that initial amount and the maturity amount. [Refer: Financial liabilities]

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The amount of non-derivative financial assets with fixed or determinable payments that are not quoted in an active market, other than: (a) those that the entity intends to sell immediately or in the near term, which shall be classified as held for trading, and those that the entity, upon initial recognition, designates as at fair value through profit or loss; (b) those that the entity, upon initial recognition, designates as available for sale; or (c) those for which the holder may not recover substantially all of its initial investment, other than because of credit deterioration, which shall be classified as available for sale. An interest acquired in a pool of assets that are not loans or receivables (for example, an interest in a mutual fund or a similar fund) is not a loan or receivable. [Refer: Derivative financial assets]

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