Earnings Per Share - Summary of Basic and Diluted (Net Loss) Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Numerator
Net (loss) income attributable to Alight, Inc. - basic and diluted	$ (68)	$ (11)
Denominator
Weighted-average shares outstanding - basic	476,145,761	456,838,216
Basic (net loss) earnings per share	$ (0.14)	$ (0.02)
Diluted (net loss) earnings per share	$ (0.14)	$ (0.02)

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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