Acquisitions - Preliminary Allocation of the Assets Acquired, and Liabilities Assumed (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Apr. 01, 2025	Dec. 31, 2024
Business Combination [Line Items]
Goodwill	$ 625,648		$ 540,290
OTC Global
Business Combination [Line Items]
Cash and cash equivalents		$ 39,180
Receivables from broker-dealers, clearing organizations, customers and related broker-dealers		716
Accrued commissions and other receivables, net		91,251
Loans, forgivable loans and other receivables from employees and partners, net		13,995
Fixed assets, net		3,670
Finite-lived intangible assets		219,400
Other assets		33,589
Total identifiable assets acquired		401,801
Accrued compensation		81,207
Accounts payable, accrued and other liabilities		99,986
Total liabilities assumed		181,193
Total purchase price consideration transferred		220,608
Goodwill		88,675
Net assets acquired		$ 309,283