Basis of Presentation - Reconciliation of Cash and Cash Equivalents (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 864	$ 611	$ 830
Restricted cash and restricted cash equivalents included in segregated cash and investments	3,192		4,015
Total cash, cash equivalents, restricted cash, and restricted cash equivalents	$ 4,056	$ 3,924	$ 4,845	$ 5,390