Debt and Interest Rate Derivatives - Borrowings and Repayments (Detail) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019
Debt
Debt repayments	$ 705	$ 385
New borrowings		$ 3,971
4.75% senior notes due June 2020 [Member]
Debt
Debt repayments	$ 600
Interest rate (as a percent)	4.75%
Canadian Senior Notes [Member]
Debt
Interest rate (as a percent)	2.60%
Foreign currency transaction gain (loss)	$ (17)
Tax Exempt Bonds [Member]
Debt
Debt repayments	$ 52
Tax Exempt Bonds [Member] \| Minimum [Member]
Debt
Interest rate (as a percent)	0.10%
Tax Exempt Bonds [Member] \| Maximum [Member]
Debt
Interest rate (as a percent)	4.30%
Financing leases and other [Member]
Debt
Debt repayments	$ 53
Non-cash financing lease incurred	$ 7

Amount of increase in lease obligation from new lease.

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

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Amount after tax, before reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount of cash outflow for debt, mandatory redeemable security, and principal payment for finance lease obligation.

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