Debt and Derivatives - Classification and Credit Facilities (Detail) - USD ($) $ in Millions		1 Months Ended	9 Months Ended
	Aug. 28, 2024	May 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Debt
Debt maturing or subject to remarketing within twelve months			$ 1,900
Debt classified as long-term due to intent and ability to refinance on long-term basis			1,200
Current portion of long-term debt			$ 676	$ 334
Commercial Paper Program [Member]
Debt
Debt term			397 days
Commercial paper borrowings			$ 0
Tax Exempt Bonds [Member]
Debt
Debt maturing or subject to remarketing within twelve months			110
Debt with interest rate periods that expire in the next 12 months			$ 1,200
Tax Exempt Bonds [Member] | Minimum [Member]
Debt
Interest rate (as a percent)			0.70%	0.70%
Tax Exempt Bonds [Member] | Maximum [Member]
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			$ 254
Revolving Credit Facility [Member]
Debt
Maximum capacity			3,500
Accordion option capacity		$ 1,000
Outstanding borrowings under credit facility			0
Letters of credit outstanding			171
Unused and available credit capacity			3,300
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 term	364 days
Outstanding borrowings under credit facility			$ 0
Commitment / ticking fee (as a percent)			0.065%
Term Credit Agreement [Member] | SOFR [Member] | Minimum [Member]
Debt
Spread rate (as a percent)	0.90%
Term Credit Agreement [Member] | SOFR [Member] | Maximum [Member]
Debt
Spread rate (as a percent)	1.25%
Term Credit Agreement [Member] | Base Rate [Member] | Minimum [Member]
Debt
Spread rate (as a percent)	0.00%
Term Credit Agreement [Member] | Base Rate [Member] | Maximum [Member]
Debt
Spread rate (as a percent)	0.25%
Other Letter Of Credit Lines [Member]
Debt
Letters of credit outstanding			$ 863