Segment Reporting - Schedule of Current Reportable and Recast of Segments by Revenue (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Revenue	$ 555	$ 557	$ 1,652	$ 1,704
Other
Segment Reporting Information [Line Items]
Revenue	0	7	0	26
Operating Segments \| Employer Solutions
Segment Reporting Information [Line Items]
Revenue	555	550	1,652	1,678
Operating Segments \| Employer Solutions \| Recurring
Segment Reporting Information [Line Items]
Revenue	504	497	1,518	1,535
Operating Segments \| Employer Solutions \| Project
Segment Reporting Information [Line Items]
Revenue	$ 51	$ 53	$ 134	$ 143

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 924
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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+ Details