Hedging Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure Of Detailed Information About Hedging Instruments [Line Items]

Summary of Hedging Derivative Financial Instruments

The hedging instrument was showed as follows:

	December 31, 2017
	NT$
	(In Millions)
Hedging derivative financial assets
Cash flow hedge - forward exchange contracts	$	－
Hedging derivative financial liabilities
Cash flow hedge - forward exchange contracts	$	1

Outstanding Forward Exchange Contracts

The outstanding forward exchange contracts at the balance sheet dates were as follows:

	Currency	Maturity Period	Contract Amount (Millions)
December 31, 2017
Forward exchange contracts - buy	EUR/NT$	2018.03-06	EUR4/NT$142

Loss (Gain) Arising from Hedging Derivative Financial Instruments that have been Reclassified from Equity to Initial Cost of the Property, Plant and Equipment

Loss (gain) arising from the hedging derivative financial instruments that have been reclassified from equity to initial cost of the property, plant and equipment were as follows:

	Year Ended December 31, 2017
	NT$
	(In Millions)
Construction in progress and equipment to be accepted	$	(2	)

Summary of Hedging Transaction and Reclassification Affected Comprehensive Income

2018

	Comprehensive Income
							Reclassification from Equity to Profit or Loss and the Adjusted Line Item
	Hedging Gain or Loss		Amount of Hedge Ineffectiveness		Line Item in which Hedge		Amount Reclassified to P/L and			Due to Hedged Future Cash Flows No
Hedge	Recognized		Recognized in		Ineffectiveness		the Adjusted			Longer Expected
Transaction	in OCI		Profit or Loss		is Included		Line Item			to Occur
	NT$		NT$		NT$		NT$			NT$
	(In Millions)
Cash flow hedge
Forecast equipment purchases	$	2	$	—		—	$	(4	)	$	—
							Construction in progress and equipment to be accepted			Other gains and losses

2019

Comprehensive Income

Reclassification from Equity to Profit or Loss and the Adjusted Line Item

Hedging Gain or Loss

Amount of Hedge Ineffectiveness

Line Item in which Hedge

Amount Reclassified to P/L and

Due to Hedged Future Cash Flows No

Hedge

Recognized

Recognized in

Ineffectiveness

the Adjusted

Longer Expected

Transaction

in OCI

Profit or Loss

is Included

Line Item

to Occur

NT$

NT$

NT$

NT$

NT$

(In Millions)

Cash flow hedge

Forecast equipment purchases

$

(1

)

$

—

—

$

(2

)

$

—

Construction in progress and equipment to be accepted

Other gains and losses

Foreign currency risk [Member]

Disclosure Of Detailed Information About Hedging Instruments [Line Items]

Summary of Hedging Derivative Financial Instruments

The following tables summarized the information relating to the hedges for foreign currency risk.

December 31, 2018

Notional Amount

Forward

Line Item in

Carrying Amount

Change in Fair Values of Hedging Instruments Used for Calculating

Hedging Instruments

Currency

(In millions)

Maturity

Rate

Balance Sheet

Asset

Liability

Hedge Ineffectiveness

NT$

NT$

NT$

(In Millions)

Cash flow hedge

Forecast purchases - forward   exchange contracts

EUR/NT$

EUR 5/ NT$ 172

2019.03

$

34.98

Hedging financial assets (liabilities)

$

1

$

—

$

2

				Accumulated Gain or Loss on Hedging Instruments in Other Equity
Hedged Items	Change in Value of Hedged Item Used for Calculating Hedge Ineffectiveness			Continuing Hedges		Hedge Accounting No Longer Applied
	NT$			NT$		NT$
				(In Millions)
Cash flow hedge
Forecast equipment purchases	$	(2	)	$	1	$	—

December 31, 2019

Notional Amount

Forward

Line Item in

Carrying Amount

Change in Fair Values of Hedging Instruments Used for Calculating

Hedging Instruments

Currency

(In millions)

Maturity

Rate

Balance Sheet

Asset

Liability

Hedge Ineffectiveness

NT$

NT$

NT$

(In Millions)

Cash flow hedge

Forecast purchases - forward   exchange contracts

EUR/NT$

EUR 2/NT$ 84

2020.03

$

33.66

Hedging financial assets (liabilities)

$

—

$

—

$

(1

)

			Accumulated Gain or Loss on Hedging Instruments in Other Equity
Hedged Items	Change in Value of Hedged Item Used for Calculating Hedge Ineffectiveness		Continuing Hedges		Hedge Accounting No Longer Applied
	NT$		NT$		NT$
			(In Millions)
Cash flow hedge
Forecast equipment purchases	$	1	$	—	$	—