Retirement Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2020

Disclosure Of Retirement Benefit Plans [Abstract]

Amounts Included in Consolidated Balance Sheets from Obligation in Respect of Defined Benefit Plans

The amounts included in the consolidated balance sheets arising from the Company’s obligation in respect of its defined benefit plans were as follows:

	December 31
	2019			2020
	NT$			NT$
	(In Millions)
Present value of funded defined benefit obligations	$	41,197		$	39,536
Fair value of plan assets		(39,820	)		(39,494	)
Funded status - deficit	$	1,377		$	42

Net defined benefit liabilities	$	3,505		$	3,415
Net defined benefit assets		(2,128	)		(3,373	)
	$	1,377		$	42

Movements in Defined Benefit Obligation and Fair Value of Plan Assets

Movements in the defined benefit obligations and the fair value of plan assets were as follows:

	Present Value of Funded Defined Benefit Obligations			Fair Value of Plan Assets			Net Defined Benefit Liabilities (Assets)
	NT$			NT$			NT$
				(In Millions)
Balance on January 1, 2018	$	37,663		$	34,972		$	2,691
Current service cost		3,024			—			3,024
Interest expense/interest income		550			544			6
Amounts recognized in profit or loss		3,574			544			3,030
Remeasurement on the net defined benefit liability
Return on plan assets (excluding amounts included in net interest)		—			875			(875	)
Actuarial losses recognized from changes in demographic assumptions		4			—			4
Actuarial losses recognized from changes in financial assumptions		1,273			—			1,273
Actuarial losses recognized from experience adjustments		813			—			813
Amounts recognized in other comprehensive income		2,090			875			1,215
Contributions from employer		—			4,374			(4,374	)
Benefits paid		(1,738	)		(1,738	)		—
Benefits paid directly by the Company		(192	)		—			(192	)
Balance on December 31, 2018		41,397			39,027			2,370
Current service cost		2,927			—			2,927
Interest expense/interest income		400			390			10
Amounts recognized in profit or loss		3,327			390			2,937
Remeasurement on the net defined benefit liability
Return on plan assets (excluding amounts included in net interest)		—			1,338			(1,338	)
Actuarial losses recognized from changes in demographic assumptions		6			—			6
Actuarial losses recognized from changes in financial assumptions		647			—			647
Actuarial gains recognized from experience adjustments		(842	)		—			(842	)
Amounts recognized in other comprehensive income		(189	)		1,338			(1,527	)
Contributions from employer		—			2,099			(2,099	)
Benefits paid		(3,034	)		(3,034	)		—
Benefits paid directly by the Company		(304	)		—			(304	)
Balance on December 31, 2019		41,197			39,820			1,377
Current service cost		2,052			—			2,052
Interest expense/interest income		298			297			1
Amounts recognized in profit or loss		2,350			297			2,053
Remeasurement on the net defined benefit liability
Return on plan assets (excluding amounts included in net interest)		—			1,308			(1,308	)
Actuarial losses recognized from changes in financial assumptions		590			—			590
Actuarial gains recognized from experience adjustments		(475	)		—			(475	)
Amounts recognized in other comprehensive income		115			1,308			(1,193	)
Contributions from employer		—			1,964			(1,964	)
Benefits paid		(3,919	)		(3,919	)		—
Benefits paid directly by the Company		(263	)		—			(263	)
Acquired by business combinations (Note 14)		56			24			32
Balance on December 31, 2020	$	39,536		$	39,494		$	42

Pension Costs Recognized in Profit and Loss for Defined Benefit Plans

Relevant pension costs recognized in profit and loss for defined benefit plans were as follows:

	Year Ended December 31
	2018		2019		2020
	NT$		NT$		NT$
	(In Millions)
Operating costs	$	1,796	$	1,726	$	1,205
Marketing expenses		886		866		603
General and administrative expenses		164		164		121
Research and development expenses		107		103		72
	$	2,953	$	2,859	$	2,001

Principal Assumptions Used for Actuarial Valuations

The principal assumptions used for the purpose of the actuarial valuations were as follows:

Effect on Present Value of Defined Benefit Obligation Due to a Reasonably Possible Change of the Significant Actuarial Assumptions

If reasonably possible changes of the respective significant actuarial assumptions occur at the end of reporting periods, while holding all other assumptions constant, the present values of the defined benefit obligations would increase (decrease) as follows:

	December 31
	2019			2020
	NT$			NT$
	(In Millions)
Discount rates
0.5% increase	$	(1,275	)	$	(1,208	)
0.5% decrease	$	1,356		$	1,284
Expected rates of salary increase
0.5% increase	$	1,448		$	1,372
0.5% decrease	$	(1,374	)	$	(1,303	)

Summary of Sensitivity Analysis

	December 31
	2019		2020
	NT$		NT$
	(In Millions)
The expected contributions to the plan for the next year	$	2,076	$	1,932
The average duration of the defined benefit obligations	6.5-14 years		6.4-13 years

Maturity Analysis of Undiscounted Benefit Payments

As of December 31, 2020, the Company’s maturity analysis of the undiscounted benefit payments was as follows:

Year	Amount
	NT$
	(In Millions)
2021	$	3,285
2022		7,056
2023		10,669
2024		11,799
2025 and thereafter		39,497
	$	72,306

Measurement Date

December 31

Discount rates

Expected rates of salary increase

1.20%-2.00%

1.00%-2.00%