Debt - Additional Information (Details) - USD ($)		1 Months Ended						3 Months Ended		6 Months Ended
		Jan. 31, 2022	Aug. 31, 2021	Jul. 31, 2021	Aug. 31, 2020	May 31, 2020	May 31, 2017	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022		Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2019
Debt Instrument [Line Items]
Debt balance								$ 2,840,000,000		$ 2,840,000,000			$ 2,868,000,000
Amortization of financing fees and benefits										(1,000,000)
Interest expense related to debt instruments								28,000,000		55,000,000
Alight Holdings
Debt Instrument [Line Items]
Amortization of financing fees and benefits												$ 9,000,000
Interest expense related to debt instruments									$ 52,000,000			105,000,000
Interest Expense
Debt Instrument [Line Items]
Amortization of financing fees and benefits								1,000,000		$ 1,000,000
Interest Expense | Alight Holdings
Debt Instrument [Line Items]
Amortization of financing fees and benefits									$ 4,000,000			8,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Debt term							5 years
Maturity Date							May 01, 2022
Line of credit, maximum borrowing capacity							$ 250,000,000
Amended Revolving Credit Facility
Debt Instrument [Line Items]
Maturity Date			Aug. 31, 2026		Oct. 31, 2024					Aug. 31, 2026
Line of credit, maximum borrowing capacity			$ 294,000,000		$ 226,000,000			294,000,000		$ 294,000,000
Unused letters of credit								4,000,000		4,000,000
Proceeds from Lines of Credit										$ 0
Other
Debt Instrument [Line Items]
Maturity Date										Jun. 30, 2022
Principal payment										$ 110,000,000
Termination date										Jun. 29, 2022
Debt instrument, borrowings offset amount								$ 104,000,000		$ 104,000,000
Revolving credit facility acquired														$ 20,000,000
Term Loan
Debt Instrument [Line Items]
Debt term							7 years
Repayments of principal to refinance debt					$ 270,000,000
Maturity Date										May 01, 2024
Repayment of principal				$ 556,000,000
Term Loan | LIBOR | Minimum
Debt Instrument [Line Items]
Debt instrument, variable interest rate					2.75%
Term Loan | LIBOR | Maximum
Debt Instrument [Line Items]
Debt instrument, variable interest rate					3.00%
Term Loan, Amended
Debt Instrument [Line Items]
Debt balance					$ 1,986,000,000
Maturity Date					Oct. 31, 2026					Oct. 31, 2026
Debt instrument, variable interest rate basis										1‑month
Payment terms										The Company is required to make principal payments at the end of each fiscal quarter based on defined terms in the agreement with the remaining principal balances due on the maturity dates.
Principal payment										$ 16,000,000
Swap agreement expiration period										2026-12
Term Loan, Amended | Alight Holdings
Debt Instrument [Line Items]
Principal payment												$ 13,000,000
Term Loan, Amended | Minimum
Debt Instrument [Line Items]
Debt instrument, variable interest rate					0.50%
Term Loan, Third Incremental
Debt Instrument [Line Items]
Debt balance			$ 525,000,000
Maturity Date		Aug. 31, 2028	Aug. 31, 2028							Aug. 31, 2028	[1]
Secured Senior Notes
Debt Instrument [Line Items]
Maturity Date						Jun. 01, 2025				Jun. 01, 2025
Payment terms										interest at a fixed rate of 5.75% per annum, payable semi-annually on June 1 and December 1 of each year
Face amount						$ 300,000,000
Interest rate						5.75%
Debt payment beginning date						Dec. 01, 2020
Term Loan, B-1
Debt Instrument [Line Items]
Maturity Date	[2]									Aug. 31, 2028
Term Loan, B-1 | SOFR
Debt Instrument [Line Items]
Debt instrument, variable interest rate					3.00%

[1] The net balance for the Third Incremental Term Loan at December 31, 2021 includes unamortized debt issuance costs of $6 million.

[2] The net balance for the B-1 Term Loan at June 30, 2022 includes unamortized debt issuance costs of $9 million.