Debt - Components (Detail) $ in Millions, $ in Millions	Sep. 30, 2022 USD ($)	Sep. 30, 2022 CAD ($)	Dec. 31, 2021 USD ($)
Debt
Debt	$ 14,063		$ 13,405
Debt issuance costs, discounts and other	(82)		(80)
Current portion of long-term debt	258		708
Long-term debt, less current portion	13,805		12,697
Commercial Paper Program [Member]
Debt
Debt	$ 840		$ 1,778
Weighted average interest rate	2.10%	2.10%	0.40%
Term Loan [Member]
Debt
Debt	$ 1,000
Interest rate (as a percent)	3.80%	3.80%
Senior Notes, Aggregate [Member]
Debt
Debt	$ 8,626		$ 8,126
Weighted average interest rate	3.20%	3.20%	3.10%
Senior Notes, Aggregate [Member] \| Minimum [Member]
Debt
Interest rate (as a percent)	0.75%	0.75%
Senior Notes, Aggregate [Member] \| Maximum [Member]
Debt
Interest rate (as a percent)	7.75%	7.75%
Canadian Senior Notes [Member]
Debt
Debt	$ 362	$ 500	$ 395
Interest rate (as a percent)	2.60%	2.60%
Tax Exempt Bonds [Member]
Debt
Debt	$ 2,619		$ 2,619
Weighted average interest rate	2.20%	2.20%	1.40%
Tax Exempt Bonds [Member] \| Minimum [Member]
Debt
Interest rate (as a percent)	0.30%	0.30%
Tax Exempt Bonds [Member] \| Maximum [Member]
Debt
Interest rate (as a percent)	4.30%	4.30%
Financing leases and other [Member]
Debt
Debt	$ 698		$ 567
Weighted average interest rate	4.70%	4.70%	4.50%

Amount of short-term and long-term debt and lease obligation.

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Amount of debt and lease obligation, classified as current.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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Weighted average interest rate of debt outstanding.

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Amount of long-term debt and lease obligation, classified as noncurrent.

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