Derivative Financial Instruments - Additional Information (Detail)	6 Months Ended
Jun. 30, 2021
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative instruments objectives	We use derivatives to partially offset our exposure to foreign currency, interest rate, aluminum and other commodity price risks. We may enter into forward contracts, option contracts, swaps, collars or other derivative instruments to offset some of the risk on expected future cash flows and on certain existing assets and liabilities.
Maximum length of time, foreign currency cash flow hedge	48 months

- Definition

Description of the reasons for holding or issuing derivative instruments and nonderivative hedging instruments. Includes discussion of the objectives for holding or issuing derivative instruments, the context needed to understand those objectives, and the strategies for achieving those objectives. The description generally distinguishes between derivative and nonderivative instruments by the types of hedging relationships and between those instruments used for risk management purposes and those used for other purposes. Information about those instruments is disclosed in the context of each instrument's primary underlying risk exposure (for example, interest rate, credit, foreign exchange rate, interest rate and foreign exchange rate, or overall price).

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