Receivables from and Payables to Broker-dealers, Clearing Organizations and Customers - Schedule of Receivables from and Payables to Broker-dealers, Clearing Organizations and Customers (Detail) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Receivables from broker-dealers, clearing organizations and customers:
Securities failed-to-deliver - broker-dealers and clearing organizations	$ 136,018	$ 109,307
Securities failed-to-deliver - customers	242,028	136,424
Cash deposits with clearing organizations and broker-dealers	110,544	107,652
Other	5,023	4,345
Total	493,613	357,728
Payables to broker-dealers, clearing organizations and customers:
Securities failed-to-receive - broker-dealers and clearing organizations	214,810	158,694
Securities failed-to-receive - customers	93,716	51,916
Other	10,340	8,235
Total	$ 318,866	$ 218,845