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Face (par) amount of debt instrument at time of issuance.

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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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Debt and Interest Rate Derivatives - Borrowings and Repayments (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	May 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Debt
Debt repayments		$ 25	$ 56
Senior Notes, Aggregate [Member]
Debt
Debt instrument face amount	$ 4,000
Senior Notes, Mandatory Redemption Feature [Member]
Debt
Debt instrument face amount	$ 3,000
Redemption price percentage	101.00%
Canadian Senior Notes [Member]
Debt
Foreign currency transaction gain (loss)		(30)
Financing leases and other [Member]
Debt
Debt repayments		25
Non-cash financing lease incurred		$ 5