Cash and Cash Equivalents and Restricted Cash - Summary of Reconciliation of Cash and Cash Equivalents with Restricted or Segregated Cash (Detail) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents	$ 544,478	$ 451,280
Cash segregated under federal regulations	47,107	45,122
Total	700,459	611,672	$ 572,664
Cash and cash equivalents
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents	544,478	451,280	430,746
Cash Segregated under Federal Regulations [Member]
Cash And Cash Equivalents [Line Items]
Cash segregated under federal regulations	47,107	45,122	50,947
Receivables from Broker-Dealers, Clearing Organizations and Customers [Member]
Cash And Cash Equivalents [Line Items]
Restricted cash deposits with clearing organizations and broker-dealers	107,652	115,151	88,923
Prepaid Expenses and Other Assets [Member]
Cash And Cash Equivalents [Line Items]
Other cash deposits	$ 1,222	$ 119	$ 2,048