Short-Term Debt - Credit Facilities (Detail) - USD ($)	Dec. 31, 2022	Dec. 31, 2021	Dec. 17, 2021
Line Of Credit Facility [Line Items]
Credit Facilities	$ 1,200,000,000	$ 1,300,000,000
Borrowings Outstanding	1,019,000,000	745,000,000
Letters of Credit Outstanding	1,000,000	1,000,000
Credit Facilities [Member]
Line Of Credit Facility [Line Items]
Borrowings Outstanding		500,000,000
Letters of Credit Outstanding	400,000,000
Commercial Paper [Member]
Line Of Credit Facility [Line Items]
Borrowings Outstanding	619,000,000	245,000,000
5-year Facility [Member]
Line Of Credit Facility [Line Items]
Credit Facilities	800,000,000	800,000,000	$ 800,000,000
Letters of Credit Outstanding	1,000,000	1,000,000
5-year Facility [Member] | Credit Facilities [Member]
Line Of Credit Facility [Line Items]
Borrowings Outstanding		0
Letters of Credit Outstanding	0
5-year Facility [Member] | Commercial Paper [Member]
Line Of Credit Facility [Line Items]
Borrowings Outstanding	619,000,000	245,000,000
1-year Term Facility [Member]
Line Of Credit Facility [Line Items]
Credit Facilities	400,000,000	500,000,000
Letters of Credit Outstanding	0	0
1-year Term Facility [Member] | Credit Facilities [Member]
Line Of Credit Facility [Line Items]
Borrowings Outstanding		500,000,000
Letters of Credit Outstanding	400,000,000
1-year Term Facility [Member] | Commercial Paper [Member]
Line Of Credit Facility [Line Items]
Borrowings Outstanding	$ 0	$ 0