Segment Reporting - Schedule of Current Reportable and Recast of Segments by Segment Profit (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Selling, general and administrative	$ 193	$ 157	$ 378	$ 297
Depreciation and intangible amortization	85	85	170	170
Operating Income (Loss)	(21)	(23)	(34)	(25)
(Gain) Loss from change in fair value of financial instruments		(50)	25	(63)
(Gain) loss from change in fair value of tax receivable agreement	11	(38)	19	(43)
Interest expense	33	29	66	58
Other (income) expense, net	4	(7)	7	(8)
Income (Loss) Before Taxes	(69)	43	(151)	31
Alight Holdings
Segment Reporting Information [Line Items]
Segment Profit	257	219	514	442
Selling, general and administrative	193	157	378	297
Depreciation and intangible amortization	85	85	170	170
Operating Income (Loss)	(21)	(23)	(34)	(25)
(Gain) Loss from change in fair value of financial instruments		(50)	25	(63)
(Gain) loss from change in fair value of tax receivable agreement	11	(38)	19	(43)
Interest expense	33	29	66	58
Other (income) expense, net	4	(7)	7	(8)
Income (Loss) Before Taxes	(69)	43	(151)	31
Employer Solutions
Segment Reporting Information [Line Items]
Segment Profit	240	200	478	404
Professional Services
Segment Reporting Information [Line Items]
Segment Profit	19	20	38	39
Other
Segment Reporting Information [Line Items]
Segment Profit	$ (2)	$ (1)	$ (2)	$ (1)