Pension And Other Retirement Benefits - Summary Of Pre Tax Amounts Recognized In Other Comprehensive Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (loss)/gain arising during the period	$ (32)	$ 6	$ 21
U.S. Plans | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Amortization of net actuarial losses	4	6	9
Net actuarial (loss)/gain arising during the period	(24)	2	21
Total recognized in OCI – pre-tax	(20)	8	30
U.S. Plans | Other Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Amortization of net actuarial losses	0	0	0
Net actuarial (loss)/gain arising during the period	(6)	3	1
Total recognized in OCI – pre-tax	$ (6)	$ 3	$ 1