Fair Value Measurement - Summary of Changes in Deferred Contingent Consideration Liabilities (Details) - USD ($) $ in Millions |
6 Months Ended | 12 Months Ended | |
|---|---|---|---|
Dec. 31, 2021 |
Jun. 30, 2021 |
Dec. 31, 2020 |
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | |||
| Beginning balance | $ 29 | ||
| Acquisitions | $ 8 | ||
| Accretion of contingent consideration | 0 | ||
| Remeasurement of acquisition-related contingent consideration | (2) | ||
| Payments | (2) | ||
| Ending Balance | 33 | $ 29 | |
| Alight Holdings [Member] | |||
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | |||
| Beginning balance | $ 29 | 26 | 22 |
| Acquisitions | 2 | 3 | |
| Accretion of contingent consideration | 1 | ||
| Remeasurement of acquisition-related contingent consideration | 8 | ||
| Payments | (7) | ||
| Ending Balance | $ 29 | $ 26 | |