Segment Reporting (Narrative) (Details)	3 Months Ended
	Mar. 31, 2025 Segment
Segment Reporting Information [Line Items]
Number of business segments	3
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]	Chairman And Chief Executive Officer [Member]
Segment Reporting, Expense Information Used by CODM, Description	Our CODM regularly reviews segment net revenues, compensation and benefits expense, non-compensation operating expenses, and income before income taxes. Amounts included in non-compensation operating expenses include “Occupancy and equipment rental,” “Communications and office supplies,” “Commissions and floor brokerage,” “Provision for credit losses,” and “Other operating expenses.”
Segment Reporting, Other Segment Item, Composition, Description	The Other segment includes interest income from stock borrow activities, unallocated interest expense, interest income and gains and losses from investments held, amortization of stock-based awards, and all unallocated overhead cost associated with the execution of orders; processing of securities transactions; custody of client securities; receipt, identification, and delivery of funds and securities; compliance with regulatory and legal requirements; internal financial accounting and controls; and general administration and acquisition charges
Global Wealth Management [Member]
Segment Reporting Information [Line Items]
Number of businesses within operating segment	2