Segment Reporting - Schedule of Current Reportable and Recast of Segments by Segment Profit (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Selling, general and administrative	$ 146	$ 151
Depreciation and intangible amortization	76	76
Operating Income (Loss) From Continuing Operations	(40)	(40)
(Gain) Loss from change in fair value of financial instruments	21	25
(Gain) loss from change in fair value of tax receivable agreement	55	8
Interest expense	31	33
Other (income) expense, net	1	1
Income (Loss) From Continuing Operations Before Taxes	(148)	(107)
Alight Holdings
Segment Reporting Information [Line Items]
Segment Profit	182	187
Selling, general and administrative	146	151
Depreciation and intangible amortization	76	76
Operating Income (Loss) From Continuing Operations	(40)	(40)
(Gain) Loss from change in fair value of financial instruments	21	25
(Gain) loss from change in fair value of tax receivable agreement	55	8
Interest expense	31	33
Other (income) expense, net	1	1
Income (Loss) From Continuing Operations Before Taxes	(148)	(107)
Employer Solutions
Segment Reporting Information [Line Items]
Segment Profit	$ 182	$ 187