Debt and Derivatives - Classification and Credit Facilities (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	May 31, 2024	Dec. 31, 2024	Oct. 31, 2024	Aug. 28, 2024	Dec. 31, 2023
Debt
Debt maturing or subject to remarketing within twelve months		$ 4,000
Current portion of long-term debt		1,359			$ 334
Tax Exempt Bonds [Member]
Debt
Debt maturing or subject to remarketing within twelve months		298
Debt with interest rate periods that expire in the next 12 months		1,400
Debt classified as long-term due to intent and ability to refinance on long-term basis		$ 2,600
Tax Exempt Bonds [Member] | Minimum [Member]
Debt
Interest rate (as a percent)		0.70%
Tax Exempt Bonds [Member] | Maximum [Member]
Debt
Interest rate (as a percent)		4.80%
Commercial Paper Program [Member]
Debt
Debt maturing or subject to remarketing within twelve months		$ 1,200
Debt term		397 days
Commercial paper borrowings		$ 1,200
3.125% senior notes due March 2025 [Member]
Debt
Debt maturing or subject to remarketing within twelve months		$ 422
Interest rate (as a percent)		3.125%
0.750% senior notes due 2025 [Member]
Debt
Debt maturing or subject to remarketing within twelve months		$ 500
Interest rate (as a percent)		0.75%
Financing leases and other [Member]
Debt
Debt maturing or subject to remarketing within twelve months		$ 438
Revolving Credit Facility [Member]
Debt
Maximum capacity		3,500
Accordion option capacity	$ 1,000
Outstanding borrowings under credit facility		0
Letters of credit outstanding		224
Unused and available credit capacity		2,100
Revolving Credit Facility [Member] | Minimum [Member]
Debt
Spread rate (as a percent)	0.585%
Revolving Credit Facility [Member] | Maximum [Member]
Debt
Spread rate (as a percent)	1.025%
Credit Facility Revolving Canadian [Member]
Debt
Maximum capacity	$ 375
Term Credit Agreement [Member]
Debt
Maximum capacity				$ 7,200
Debt instrument face amount			$ 5,200
Other Letter Of Credit Lines [Member]
Debt
Letters of credit outstanding		$ 862