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, 2024	Dec. 31, 2023
Receivables from broker-dealers, clearing organizations and customers:
Securities failed-to-deliver - broker-dealers and clearing organizations	$ 262,239	$ 282,125
Securities failed-to-deliver - customers	282,172	284,322
Deposits with clearing organizations and broker-dealers	112,713	115,151
Other	5,764	6,338
Total	662,888	687,936
Payables to broker-dealers, clearing organizations and customers:
Securities failed-to-receive - broker-dealers and clearing organizations	169,798	125,022
Securities failed-to-receive - customers	287,086	405,186
Other	8,819	7,190
Total	$ 465,703	$ 537,398