Retirement Plans (Tables)

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Schedule of changes in projected benefit obligation, fair value of plan assets and funded status of plan

Changes in Benefit Obligations and Plan Assets

	As of December 31
(Dollars in millions)	2020		2019
Benefit obligation at beginning of year	$	54	$	76
Service cost	4		4
Interest cost	1		1
Actuarial (gain) loss	(7)		6
Benefits paid	(3)		(2)
Net of Held for sales add back/Divestiture	7		—
Translation difference	4		1
Held for sale	—		(32)
Benefit obligation at end of year	$	60	$	54
Fair value of plan assets at beginning of year	$	37	$	54
Actual return on plan assets	3		6
Company contributions	3		2
Benefits paid	(3)		(2)
Net of Held for sales add back/Divestiture	(1)		—
Translation difference	1		1
Held for sale	—		(24)
Fair value of plan assets at year end	$	40	$	37
Funded status recognized in the balance sheet	$	(20)	$	(17)

Schedule of net periodic benefit cost

Components of Net Periodic Benefit Cost Associated with the Defined Benefit Retirement Plan

	Year Ended December 31
(Dollars in millions)	2020		2019		2018
Service cost	$	4	$	4	$	5
Interest cost	1		1		2
Expected return on plan assets	(2)		(2)		(2)
Amortization of actuarial loss	1		1		—
Net periodic benefit cost	$	4	$	4	$	4

Schedule of amounts recognized in other comprehensive income (loss)

Components of Accumulated other Comprehensive Income Before Tax

	As of December 31
(Dollars in millions)	2020		2019
Net actuarial loss	$	15	$	7
Total accumulated other comprehensive loss recognized in the balance sheet	$	15	$	7

Changes in Accumulated Other Comprehensive Income Before Tax

	As of December 31
(Dollars in millions)	2020		2019
Total retirement benefit recognized in accumulated other comprehensive income at beginning of year	$	13	$	10
Held for sale	—		2
Add back Held for sale	(2)		—
Effect of plan combinations	11		—
Net actuarial loss (gain)	(8)		2
Amortization of actuarial loss	(1)		(1)
Translation difference	2		—
Total retirement benefit recognized in accumulated other comprehensive income at end of year	$	15	$	13

Schedule of accumulated and projected benefit obligations in excess of fair value

Pension Plans for Which Accumulated Benefit Obligation (ABO) Exceeds the Fair Value of Plan Assets

	As of December 31
(Dollars in millions)	2020		2019
Projected Benefit Obligation (PBO)	$	60	$	54
Accumulated Benefit Obligation	$	54	$	48
Fair value of plan assets	$	40	$	37

Schedule of assumptions used

Assumptions Used to Determine the Benefit Obligation

	As of December 31
	2020		2019
	Weighted average
Discount rate	2.32	%	1.86	%
Rate of increases in compensation level	3.30	%	4.33	%

 Assumptions Used to Determine the Net Periodic Benefit Cost for Years Ended December 31

	Year Ended December 31
	2020		2019		2018
	Weighted average
Discount rate	1.86	%	2.14	%	2.06	%
Rate of increases in compensation level	4.33	%	4.39	%	4.3	%
Expected long-term rate of return on assets	3.76	%	3.49	%	3.81	%

Schedule of allocation of plan assets

Fair Value of Total Plan Assets

	As of December 31
ASSETS CATEGORY IN % WEIGHTED AVERAGE	2020		2019
Equity securities	65	%	70	%
Debt instruments	22	%	21	%
Other assets	13	%	9	%
Total	100	%	100	%

The following table summarizes the fair value of the defined benefit pension plan assets: 

	As of December 31
(Dollars in millions)	2020		2019
Assets
Equity
U.S. Large Cap	$	6	$	10
Non-U.S. Equity	20		16
Non-U.S. Bonds
Corporate	4		5
Aggregate	5		3
Other Investments	5		3
Total	$	40	$	37

Schedule of expected benefit payments

Pension Benefits Expected Payments (Dollars in millions)	Amount
2021	$	2
2022	$	2
2023	$	3
2024	$	3
2025	$	3
Years 2026-2030	$	17