v3.26.1
Fair Value Measurements - Financial Assets and Liabilities Measured on a Recurring and Nonrecurring Basis (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
Jun. 30, 2025
Assets      
Restricted cash $ 232,889 $ 225,298 $ 116,675
Securities owned — trading 188,006 76,108  
Fair Value, Recurring      
Assets      
Restricted cash 138,459 127,585  
Securities owned — trading 188,006 76,108  
Other assets 1,671,561 1,471,620  
Total assets at fair value 2,577,023 2,601,024  
Other liabilities:      
Securities sold, but not yet purchased 292 174  
Total other liabilities 529,686 495,895  
Total liabilities at fair value 529,686 495,895  
Fair Value, Recurring | Level 1      
Assets      
Restricted cash 138,459 127,585  
Securities owned — trading 187,967 76,093  
Other assets 1,669,635 1,469,197  
Total assets at fair value 2,575,058 2,598,586  
Other liabilities:      
Securities sold, but not yet purchased 42 174  
Total other liabilities 421,804 371,857  
Total liabilities at fair value 421,804 371,857  
Fair Value, Recurring | Level 2      
Assets      
Restricted cash 0 0  
Securities owned — trading 39 15  
Other assets 1,926 2,423  
Total assets at fair value 1,965 2,438  
Other liabilities:      
Securities sold, but not yet purchased 250 0  
Total other liabilities 250 0  
Total liabilities at fair value 250 0  
Fair Value, Recurring | Level 3      
Assets      
Restricted cash 0 0  
Securities owned — trading 0 0  
Other assets 0 0  
Total assets at fair value 0 0  
Other liabilities:      
Securities sold, but not yet purchased 0 0  
Total other liabilities 107,632 124,038  
Total liabilities at fair value 107,632 124,038  
Equity securities | Fair Value, Recurring      
Other liabilities:      
Securities sold, but not yet purchased 42 174  
Equity securities | Fair Value, Recurring | Level 1      
Other liabilities:      
Securities sold, but not yet purchased 42 174  
Equity securities | Fair Value, Recurring | Level 2      
Other liabilities:      
Securities sold, but not yet purchased 0 0  
Equity securities | Fair Value, Recurring | Level 3      
Other liabilities:      
Securities sold, but not yet purchased 0 0  
Debt Securities | Fair Value, Recurring      
Other liabilities:      
Securities sold, but not yet purchased 250    
Debt Securities | Fair Value, Recurring | Level 1      
Other liabilities:      
Securities sold, but not yet purchased 0    
Debt Securities | Fair Value, Recurring | Level 2      
Other liabilities:      
Securities sold, but not yet purchased 250    
Debt Securities | Fair Value, Recurring | Level 3      
Other liabilities:      
Securities sold, but not yet purchased 0    
Cash equivalents | Fair Value, Recurring      
Assets      
Cash equivalents 55,840 104,377  
Cash equivalents | Fair Value, Recurring | Level 1      
Assets      
Cash equivalents 55,840 104,377  
Cash equivalents | Fair Value, Recurring | Level 2      
Assets      
Cash equivalents 0 0  
Cash equivalents | Fair Value, Recurring | Level 3      
Assets      
Cash equivalents 0 0  
Cash equivalents segregated under federal or other regulations | Fair Value, Recurring      
Assets      
Cash equivalents 523,157    
Cash equivalents segregated under federal or other regulations | Fair Value, Recurring | Federal Or Other Regulations      
Assets      
Cash equivalents   821,334  
Cash equivalents segregated under federal or other regulations | Fair Value, Recurring | Level 1 | Federal Or Other Regulations      
Assets      
Cash equivalents 523,157 821,334  
Cash equivalents segregated under federal or other regulations | Fair Value, Recurring | Level 2 | Federal Or Other Regulations      
Assets      
Cash equivalents 0 0  
Cash equivalents segregated under federal or other regulations | Fair Value, Recurring | Level 3 | Federal Or Other Regulations      
Assets      
Cash equivalents 0 0  
Mutual funds      
Assets      
Securities owned — trading 140,031 40,029  
Mutual funds | Fair Value, Recurring      
Assets      
Securities owned — trading 45,194 40,029  
Mutual funds | Fair Value, Recurring | Level 1      
Assets      
Securities owned — trading 45,194 40,029  
Mutual funds | Fair Value, Recurring | Level 2      
Assets      
Securities owned — trading 0 0  
Mutual funds | Fair Value, Recurring | Level 3      
Assets      
Securities owned — trading 0 0  
U.S. treasury obligations | Fair Value, Recurring      
Assets      
Securities owned — trading 140,031 33,559  
U.S. treasury obligations | Fair Value, Recurring | Level 1      
Assets      
Securities owned — trading 140,031 33,559  
U.S. treasury obligations | Fair Value, Recurring | Level 2      
Assets      
Securities owned — trading 0 0  
U.S. treasury obligations | Fair Value, Recurring | Level 3      
Assets      
Securities owned — trading 0 0  
Equity securities      
Assets      
Securities owned — trading 2,742 2,505  
Equity securities | Fair Value, Recurring      
Assets      
Securities owned — trading 2,742 2,505  
Equity securities | Fair Value, Recurring | Level 1      
Assets      
Securities owned — trading 2,742 2,505  
Equity securities | Fair Value, Recurring | Level 2      
Assets      
Securities owned — trading 0 0  
Equity securities | Fair Value, Recurring | Level 3      
Assets      
Securities owned — trading 0 0  
Debt securities      
Assets      
Securities owned — trading 39 15  
Debt securities | Fair Value, Recurring      
Assets      
Securities owned — trading 39 15  
Debt securities | Fair Value, Recurring | Level 1      
Assets      
Securities owned — trading 0 0  
Debt securities | Fair Value, Recurring | Level 2      
Assets      
Securities owned — trading 39 15  
Debt securities | Fair Value, Recurring | Level 3      
Assets      
Securities owned — trading 0 0  
Deferred compensation plan | Fair Value, Recurring      
Assets      
Other assets 1,247,873 1,097,514  
Deferred compensation plan | Fair Value, Recurring | Level 1      
Assets      
Other assets 1,247,873 1,097,514  
Deferred compensation plan | Fair Value, Recurring | Level 2      
Assets      
Other assets 0 0  
Deferred compensation plan | Fair Value, Recurring | Level 3      
Assets      
Other assets 0 0  
Fractional shares — investment | Fair Value, Recurring      
Assets      
Other assets 421,762 371,683  
Other liabilities:      
Obligations 421,762 371,683  
Fractional shares — investment | Fair Value, Recurring | Level 1      
Assets      
Other assets 421,762 371,683  
Other liabilities:      
Obligations 421,762 371,683  
Fractional shares — investment | Fair Value, Recurring | Level 2      
Assets      
Other assets 0 0  
Other liabilities:      
Obligations 0 0  
Fractional shares — investment | Fair Value, Recurring | Level 3      
Assets      
Other assets 0 0  
Other liabilities:      
Obligations 0 0  
Other investments | Fair Value, Recurring      
Assets      
Other assets 1,926 2,423  
Other investments | Fair Value, Recurring | Level 1      
Assets      
Other assets 0 0  
Other investments | Fair Value, Recurring | Level 2      
Assets      
Other assets 1,926 2,423  
Other investments | Fair Value, Recurring | Level 3      
Assets      
Other assets 0 0  
Contingent consideration | Fair Value, Recurring      
Other liabilities:      
Obligations 107,632 124,038  
Contingent consideration | Fair Value, Recurring | Level 1      
Other liabilities:      
Obligations 0 0  
Contingent consideration | Fair Value, Recurring | Level 2      
Other liabilities:      
Obligations 0 0  
Contingent consideration | Fair Value, Recurring | Level 3      
Other liabilities:      
Obligations $ 107,632 $ 124,038