Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($)
$ in Millions
 6 Months Ended 12 Months Ended
Dec. 31, 2021
Jun. 30, 2021
Dec. 31, 2020
Dec. 31, 2019
Revenue $ 1,554 $ 1,361 $ 2,728 $ 2,552
Cost of services, exclusive of depreciation and amortization 1,001      
Depreciation and amortization 21      
Gross Profit 532      
Operating Expenses        
Selling, general and administrative 304      
Depreciation and intangible amortization 163      
Total operating expenses 467      
Operating Income 65 102 147 265
Other Expense        
Loss from change in fair value of financial instruments 65      
Gain from change in fair value of tax receivable agreement (37)      
Interest expense 57 123 234 224
Other expense, net 3 9 7 3
Total other expense, net 88      
(Loss) Income Before Income Tax Expense (Benefit) (23) (30) (94) 38
Income tax expense (benefit) 25 (5) 9 16
Net (Loss) Income (48)      
Net loss attributable to noncontrolling interests (13)      
Net (Loss) Income Attributable to Alight, Inc. $ (35)      
Earnings Per Share        
Basic net loss per share $ (0.08)      
Diluted net loss per share $ (0.08)      
Other comprehensive (loss) income, net of tax:        
Change in fair value of derivatives $ 9      
Total other comprehensive income (loss), net of tax: 9      
Comprehensive (Loss) Income Before Noncontrolling Interests (39)      
Comprehensive loss attributable to noncontrolling interests (12)      
Comprehensive (Loss) Income Attributable to Alight, Inc. $ (27) 6 (120) (6)
Alight Holdings        
Revenue   1,361 2,728 2,552
Cost of services, exclusive of depreciation and amortization   888 1,829 1,619
Depreciation and amortization   38 65 50
Gross Profit   435 834 883
Operating Expenses        
Selling, general and administrative   222 461 415
Depreciation and intangible amortization   111 226 203
Total operating expenses   333 687 618
Operating Income   102 147 265
Other Expense        
Interest expense   123 234 224
Other expense, net   9 7 3
Total other expense, net   132 241 227
(Loss) Income Before Income Tax Expense (Benefit)   (30) (94) 38
Income tax expense (benefit)   (5) 9 16
Net (Loss) Income   (25) (103) 22
Net (Loss) Income Attributable to Alight, Inc.   (25) (103) 22
Other comprehensive (loss) income, net of tax:        
Change in fair value of derivatives   23 (25) (34)
Foreign currency translation adjustments   8 8 6
Total other comprehensive income (loss), net of tax:   31 (17) (28)
Comprehensive (Loss) Income Before Noncontrolling Interests   6 (120) (6)
Comprehensive (Loss) Income Attributable to Alight, Inc.   $ 6 $ (120) $ (6)