Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities - Additional Information (Details) - USD ($) $ in Millions			3 Months Ended		9 Months Ended
	Jun. 11, 2024	Mar. 15, 2023	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Noncash or Part Noncash Acquisitions [Line Items]
Amount received from settlement of contingent payments			$ 57
Net proceeds from issuance of the notes					$ 599
Deferred federal income tax payments amounts due to Hurricane Idalia Tax Relief					50		$ 91
Payments of accrued federal income tax payments due		$ 31
Tax payments associated with gain on disposal of businesses sold				$ 30
Effect of foreign exchange rate changes on cash and cash equivalents inclusive of fiduciary cash					$ 45	$ 2
5.650% Senior Notes, Semi-Annual Interest Payments, Net of the Unamortized Discount, Balloon Due 2034
Noncash or Part Noncash Acquisitions [Line Items]
Debt instrument, face amount	$ 600
Debt instrument interest rate stated percentage	5.65%				5.65%		5.65%
Net proceeds from issuance of the notes	$ 593
4.200% Senior Notes Due 2024
Noncash or Part Noncash Acquisitions [Line Items]
Debt instrument interest rate stated percentage					4.20%		4.20%