Lease Obligations - Additional Information (Details) $ in Millions	Dec. 31, 2023 USD ($)
Leases [Abstract]
Operating lease future lease payments include sublease rental income 2024	$ 5
Operating lease future lease payments include sublease rental income 2025	$ 2

Lessee operating lease liability payments include sublease rental income due next twelve months.

No definition available.

Name:	alit_LesseeOperatingLeaseLiabilityPaymentsIncludeSubleaseRentalIncomeDueNextTwelveMonths
Namespace Prefix:	alit_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant