Business combination, contingent consideration, liability expected holding period.

No definition available.

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- Definition

The seller earnout fair value of shares that would be issued, determined under the conditions specified in the contract if the settlement were to occur at the reporting date.

+ References

No definition available.

+ Details

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Namespace Prefix:	alit_
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Balance Type:	credit
Period Type:	duration

- Definition

Loss (gain) from change in fair value of seller earnouts.

+ References

No definition available.

+ Details

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Namespace Prefix:	alit_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Value of input used to measure contingent consideration liability from business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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- Details

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Financial Instruments - Seller Earnouts - Additional Information (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of seller earnouts	$ 114		$ 95
(Gain) loss from change in fair value of seller earnouts	19	$ 13
Class Z Common Stock
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
(Gain) loss from change in fair value of seller earnouts	$ 2	$ 12
Seller Earnouts Liability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Business combination, contingent consideration, liability expected holding period	4 years 3 months 3 days
Seller Earnouts Liability \| Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	45
Seller Earnouts Liability \| Risk-free Interest Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	4.28