Fair Value Information (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure of fair value measurement of assets and liabilities [Line Items]

Carrying Amounts And Fair Value of Financial Assets and Liabilities

b. Financial instruments that are measured at fair value on a recurring basis

December 31, 2018

	Level 1		Level 2		Level 3		Total
Financial assets at FVTPL
Non-listed stocks	$	—	$	—	$	517	$	517
Hedging financial assets	$	—	$	1	$	—	$	1
Financial assets at FVOCI
Equity investment	$	2,900	$	—	$	4,033	$	6,933
Financial liabilities at FVTPL
Derivatives	$	—	$	1	$	—	$	1

December 31, 2019

	Level 1		Level 2		Level 3		Total
Financial assets at FVTPL
Derivatives	$	—	$	—	$	—	$	—
Listed stocks		1		—		—		1
Non-listed stocks		—		—		778		778
	$	1	$	—	$	778	$	779
Hedging financial assets	$	—	$	—	$	—	$	—
Financial assets at FVOCI
Equity investment	$	2,454	$	—	$	4,700	$	7,154
Financial liabilities at FVTPL
Derivatives	$	—	$	—	$	—	$	—

Schedule of Percentage Decrease in Discount for Lack of Marketability or Noncontrolling Interests

A decrease in discount for the lack of marketability or noncontrolling interests discount would result in increases in the fair values.

	December 31
	2018	2019
Discount for lack of marketability	12.73%-20.00%	13.73%-20.00%
Noncontrolling interests discount	24.41%-25.00%	21.45%-25.00%

Schedule of Impact of Decrease in Discount for Lack of Marketability or Noncontrolling Interests

	December 31
	2019		2019
	NT$		NT$
	(In Millions)
Discount for lack of marketability     5% decrease	$	268	$	342
Noncontrolling interests discount     5% decrease	$	37	$	54

Level 3 [Member]

Disclosure of fair value measurement of assets and liabilities [Line Items]

Schedule of Reconciliations for Financial Assets

The reconciliations for financial assets measured at Level 3 are listed below:

2018

Financial Assets	Measured at Fair Value through Profit or Loss			Measured at Fair Value through Other Comprehensive Income			Total
	NT$			NT$			NT$
				(In Millions)
Balance at January 1, 2018 (IAS 39)	$	—		$	—		$	—
The effect on retrospective adjustment of applying IFRS 9		543			3,925			4,468
Balance at January 1, 2018 (IFRS 9)		543			3,925			4,468
Acquisition		—			290			290
Recognized in profit or loss under “Other gains and losses”		(26	)		—			(26	)
Recognized in other comprehensive income under “Unrealized    gain or loss on investments in equity instruments at fair    value through other comprehensive income”		—			(175	)		(175	)
Proceeds from return of investees		—			(7	)		(7	)
Balance at December 31, 2018	$	517		$	4,033		$	4,550
Unrealized loss in 2018	$	(26	)

2019

Financial Assets	Measured at Fair Value through Profit or Loss			Measured at Fair Value through Other Comprehensive Income			Total
	NT$			NT$			NT$
				(In Millions)
Balance at January 1, 2019	$	517		$	4,033		$	4,550
Acquisition		300			—			300
Recognized in profit or loss under “Other gains and losses”		(39	)		—			(39	)
Recognized in other comprehensive income under “Unrealized    gain or loss on investments in equity instruments at fair    value through other comprehensive income”		—			676			676
Proceed from return of investments		—			(9	)		(9	)
Balance at December 31, 2019	$	778		$	4,700		$	5,478
Unrealized loss in 2019	$	(39	)