Debt and Derivatives - Classification and Utilization (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	May 31, 2022
Debt
Debt maturing or subject to remarketing within twelve months	$ 3,600
Current portion of long-term debt	513	$ 414
Debt classified as long-term due to intent and ability to refinance on long-term basis	3,100
Carrying value of debt	15,368	14,984
Revolving Credit Facility [Member]
Debt
Maximum capacity	3,500
Outstanding borrowings under credit facility	0
Letters of credit outstanding	179
Unused and available credit capacity	2,000
Term Loan maturing May 2024 [Member]
Debt
Debt maturing or subject to remarketing within twelve months	1,000
Maximum capacity			$ 1,000
Carrying value of debt	1,000	1,000
Commercial Paper Program [Member]
Debt
Debt maturing or subject to remarketing within twelve months	$ 1,300
Debt term	397 days
Carrying value of debt	$ 1,345	1,730
Commercial paper borrowings	1,300
Tax Exempt Bonds [Member]
Debt
Debt maturing or subject to remarketing within twelve months	55
Debt with interest rate periods that expire in the next 12 months	983
Carrying value of debt	$ 2,658	$ 2,648
Tax Exempt Bonds [Member] | Minimum [Member]
Debt
Interest rate (as a percent)	0.40%	0.40%
Tax Exempt Bonds [Member] | Maximum [Member]
Debt
Interest rate (as a percent)	4.40%	4.40%
Senior Notes 3.5 % Due 2024 Member
Debt
Debt maturing or subject to remarketing within twelve months	$ 156
Interest rate (as a percent)	3.50%
Other Letter Of Credit Lines [Member]
Debt
Letters of credit outstanding	$ 802
Financing leases and other [Member]
Debt
Debt maturing or subject to remarketing within twelve months	172
Carrying value of debt	$ 702	$ 699