Income Taxes (Income before Income Taxes) (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income (loss) before income taxes	$ (578)	$ (357)	$ (296)
Domestic [Member]
Income (loss) before income taxes	(578)	(357)	(287)
Foreign [Member]
Income (loss) before income taxes	$ 0	$ 0	$ (9)

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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+ Details