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

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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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Debt - Components of Debt (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Debt
Debt	$ 13,498		$ 10,026
Debt issuance costs, discounts and other	(85)		(52)
Current portion of long-term debt	218		432
Long-term debt, less current portion	$ 13,280		9,594
Revolving Credit Facility [Member]
Debt
Debt			$ 11
Weighted average interest rate			3.10%
Commercial Paper Program [Member]
Debt
Debt			$ 990
Weighted average interest rate	2.90%
Senior Notes, Aggregate [Member]
Debt
Debt	$ 9,965		$ 6,222
Weighted average interest rate	3.90%		4.30%
Canadian Senior Notes [Member]
Debt
Debt	$ 385
Interest rate (as a percent)	2.60%	2.60%
Tax Exempt Bonds [Member]
Debt
Debt	$ 2,523		$ 2,388
Current portion of long-term debt	$ 112
Weighted average interest rate	2.30%		2.35%
Financing leases and other [Member]
Debt
Debt	$ 710		$ 467
Current portion of long-term debt	$ 218
Weighted average interest rate	4.70%
Minimum [Member] \| Senior Notes, Aggregate [Member]
Debt
Interest rate (as a percent)	2.40%
Minimum [Member] \| Tax Exempt Bonds [Member]
Debt
Interest rate (as a percent)	1.35%
Maximum [Member] \| Senior Notes, Aggregate [Member]
Debt
Interest rate (as a percent)	7.75%
Maximum [Member] \| Tax Exempt Bonds [Member]
Debt
Interest rate (as a percent)	4.30%