Pension And Other Retirement Benefits - Summary of Changes in Benefit Obligations and Fair Value of Plan Assets for Post-Retirement Plans (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in benefit obligation:
Interest cost	$ (19)	$ (22)	$ (19)
Amounts recorded on the consolidated balance sheets:
Pension and retirement benefits asset – non current	21	0
Pension and retirement benefits liability – current	(45)	(7)
Pension and retirement benefits liability – non current	(244)	(299)
U.S. Plans | Pension Plans
Change in benefit obligation:
Benefit obligation, beginning of the period	(589)	(508)
Service cost	(17)	(17)	(19)
Interest cost	(17)	(21)	(17)
Plan participants’ contributions	0	0
Benefits paid	22	21
Actuarial gain (loss)	6	(3)
Assumption changes	(68)	(61)
Benefit obligation, end of the period	(663)	(589)	(508)
Change in plan assets:
Fair value of plan assets, beginning of the period	395	348
Actual return on plan assets	45	60
Benefits paid	(22)	(21)
Employer contributions	110	8
Plan participants’ contributions	0	0
Fair value of plan assets, end of the period	528	395	348
Funded Status of the plans	(135)	(194)
Amounts recorded on the consolidated balance sheets:
Pension and retirement benefits asset – non current	21	0
Pension and retirement benefits liability – current	(44)	(6)
Pension and retirement benefits liability – non current	(112)	(188)
Net amount recognized	(135)	(194)
Accumulated benefit obligation, end of the period	(601)	(529)
U.S. Plans | Other Retirement Plans
Change in benefit obligation:
Benefit obligation, beginning of the period	(42)	(32)
Service cost	(3)	(3)	(3)
Interest cost	(1)	(1)	(1)
Plan participants’ contributions	(1)	(1)
Benefits paid	2	1
Actuarial gain (loss)	2	0
Assumption changes	(5)	(6)
Benefit obligation, end of the period	(48)	(42)	(32)
Change in plan assets:
Fair value of plan assets, beginning of the period	0	0
Actual return on plan assets	0	0
Benefits paid	(2)	(1)
Employer contributions	1	0
Plan participants’ contributions	1	1
Fair value of plan assets, end of the period	0	0	$ 0
Funded Status of the plans	(48)	(42)
Amounts recorded on the consolidated balance sheets:
Pension and retirement benefits asset – non current	0	0
Pension and retirement benefits liability – current	(1)	(1)
Pension and retirement benefits liability – non current	(47)	(41)
Net amount recognized	$ (48)	$ (42)