Summary of Significant Accounting Policies- Reconciliation of Cash and Cash Equivalents (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Cash and cash equivalents	$ 1,015	$ 611	$ 1,368
Restricted cash and restricted cash equivalents included in segregated cash and investments	4,490	3,313	4,022
Total cash, cash equivalents, restricted cash, and restricted cash equivalents	$ 5,505	$ 3,924	$ 5,390	$ 7,033