Acquisitions - Preliminary Allocation of the Assets Acquired, and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Apr. 01, 2025	Dec. 31, 2024	Dec. 31, 2023
Business Combination [Line Items]
Goodwill	$ 648,616		$ 540,290	$ 506,344
OTC Global
Business Combination [Line Items]
Cash and cash equivalents		$ 23,394
Receivables from broker-dealers, clearing organizations, customers and related broker-dealers		716
Accrued commissions and other receivables, net		91,256
Loans, forgivable loans and other receivables from employees and partners, net		13,476
Fixed assets, net		3,752
Finite-lived intangible assets		219,200
Investments		838
Other assets		33,518
Total identifiable assets acquired		386,150
Accrued compensation		86,038
Accounts payable, accrued and other liabilities		103,223
Total liabilities assumed		189,261
Net identifiable assets acquired		196,889
Goodwill		112,394
Net assets acquired		$ 309,283