Pension And Other Retirement Benefits - Summary of Post-Retirement Plans to Amortize from Accumulated Other Comprehensive Income (Loss) as Net Periodic Expense (Detail) - U.S. Plans $ in Millions	Dec. 31, 2019 USD ($)
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial losses	$ 7
Total to be recognized as components of net periodic expense	7
Other Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial losses	0
Total to be recognized as components of net periodic expense	$ 0