Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities - Schedule of Reconciliation of Cash and Cash Equivalents Inclusive of Restricted Cash (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Supplemental Cash Flow Elements [Abstract]
Restricted fiduciary cash	$ 1,470	$ 1,570
Non-restricted fiduciary cash	301	257
Total restricted and non-restricted fiduciary cash at the end of the period	1,771	1,827
Cash and cash equivalents	669	675	$ 581
Fiduciary cash	1,771		1,569
Total cash and cash equivalents inclusive of restricted cash at the end of the period	$ 2,440	$ 2,502	$ 2,150	$ 2,303