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, 2022	Dec. 31, 2021
Receivables from broker-dealers, clearing organizations and customers:
Securities failed-to-deliver - broker-dealers and clearing organizations	$ 211,401	$ 152,766
Securities failed-to-deliver - customers	418,611	182,052
Deposits with clearing organizations and broker-dealers	85,331	68,565
Other	5,784	4,963
Total	721,127	408,346
Payables to broker-dealers, clearing organizations and customers:
Securities failed-to-receive - broker-dealers and clearing organizations	268,417	166,010
Securities failed-to-receive - customers	184,124	59,879
Other	5,935	3,436
Total	$ 458,476	$ 229,325