Summary of Significant Accounting Policies - Schedule of Disaggregation of Revenue by Major Source (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Automotive [Member] \| Automotive Sales with Resale Value Guarantee, Pricing Adjustments [Member]
Disaggregation Of Revenue [Line Items]
Revenues	$ 72	$ 555

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details