Postretirement Benefit Plans - Classification of Pension Plan Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	$ 213
Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	22	$ 3
Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	128	142
Level III
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	25	22
Equity securities | Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Equity securities | Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	49	59
Equity securities | Level III
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Debt securities | Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	18	3
Debt securities | Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	38	42
Debt securities | Level III
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Insurance contracts | Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Insurance contracts | Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	14	14
Insurance contracts | Level III
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	0	0
Other | Level 1
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	4	0
Other | Level 2
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	27	27
Other | Level III
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	$ 25	$ 22