Debt - Classification and Utilization (Detail) - USD ($) $ in Millions	1 Months Ended	6 Months Ended
	May 31, 2024	Jun. 30, 2024	Dec. 31, 2023
Debt
Debt maturing or subject to remarketing within twelve months		$ 3,800
Debt classified as long-term due to intent and ability to refinance on long-term basis		3,600
Current portion of long-term debt		242	$ 334
Commercial Paper Program [Member]
Debt
Debt maturing or subject to remarketing within twelve months		1,600
Commercial paper borrowings		$ 1,600
Debt term		397 days
Tax Exempt Bonds [Member]
Debt
Debt maturing or subject to remarketing within twelve months		$ 30
Debt with interest rate periods that expire in the next 12 months		$ 1,600
Tax Exempt Bonds [Member] | Minimum
Debt
Interest rate (as a percent)		0.55%	0.55%
Tax Exempt Bonds [Member] | Maximum
Debt
Interest rate (as a percent)		5.00%	5.00%
3.125% senior notes due 2025 [Member]
Debt
Debt maturing or subject to remarketing within twelve months		$ 422
Interest rate (as a percent)		3.125%
Financing leases and other [Member]
Debt
Debt maturing or subject to remarketing within twelve months		$ 167
Revolving Credit Facility [Member]
Debt
Maximum capacity		3,500
Accordion option capacity	$ 1,000
Outstanding borrowings under credit facility		0
Letters of credit outstanding		180
Unused and available credit capacity		1,700
Revolving Credit Facility [Member] | Minimum
Debt
Spread rate (as a percent)	0.585%
Revolving Credit Facility [Member] | Maximum
Debt
Spread rate (as a percent)	1.025%
Credit Facility Revolving Canadian [Member]
Debt
Maximum capacity	$ 375
Other Letter Of Credit Lines [Member]
Debt
Letters of credit outstanding		846
Senior Notes 4.950 Percent [Member]
Debt
Debt instrument face amount		$ 1,500