Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Statement [Abstract]
Revenue	$ 2,262	$ 2,332	$ 2,386
Cost of services, exclusive of depreciation and amortization	1,386	1,442	1,504
Depreciation and amortization	111	96	72
Gross Profit	765	794	810
Operating Expenses
Selling, general and administrative	435	585	590
Depreciation and intangible amortization	296	299	301
Goodwill impairment	3,124	0	0
Total Operating expenses	3,855	884	891
Operating Income (Loss) From Continuing Operations	(3,090)	(90)	(81)
Other (Income) Expense
(Gain) Loss from change in fair value of financial instruments	(1)	(57)	10
(Gain) Loss from change in fair value of tax receivable agreement	(93)	34	118
Interest expense	92	103	131
Other (income) expense, net	(26)	(22)	(3)
Total Other (income) expense, net	(28)	58	256
Income (Loss) From Continuing Operations Before Taxes	(3,062)	(148)	(337)
Income tax expense (benefit)	16	(8)	(20)
Net Income (Loss) From Continuing Operations	(3,078)	(140)	(317)
Net Income (Loss) From Discontinued Operations, Net of Tax	(21)	(19)	(45)
Net Income (Loss)	(3,099)	(159)	(362)
Net income (loss) attributable to noncontrolling interests	(2)	(2)	(17)
Net Income (Loss) Attributable to Alight, Inc.	$ (3,097)	$ (157)	$ (345)
Basic and Diluted
Continuing operations, basic (in dollars per share)	$ (5.83)	$ (0.25)	$ (0.61)
Continuing operations, diluted (in dollars per share)	(5.83)	(0.25)	(0.61)
Discontinued operations, basic (in dollars per share)	(0.04)	(0.04)	(0.09)
Discontinued operations, diluted (in dollars per share)	(0.04)	(0.04)	(0.09)
Net income (loss), basic (in dollars per share)	(5.87)	(0.29)	(0.70)
Net income (loss), diluted (in dollars per share)	$ (5.87)	$ (0.29)	$ (0.70)
Net Income (Loss)	$ (3,099)	$ (159)	$ (362)
Other comprehensive income (loss), net of tax:
Change in fair value of derivatives	(27)	(35)	(42)
Foreign currency translation adjustments	0	7	9
Total Other comprehensive income (loss), net of tax:	(27)	(28)	(33)
Comprehensive Income (Loss) Before Noncontrolling Interests	(3,126)	(187)	(395)
Comprehensive income (loss) attributable to noncontrolling interests	(2)	(6)	(26)
Comprehensive Income (Loss) Attributable to Alight, Inc.	$ (3,124)	$ (181)	$ (369)