Receivables from/Payables to Broker-Dealers and Clearing Organizations (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Due from prime brokers	$ 418,059	$ 302,152
Deposits with clearing organizations	231,977	84,509
Net equity with futures commission merchants	267,748	294,884
Unsettled trades with clearing organization	214,618	193,544
Securities failed to deliver	178,324	218,663
Commissions and fees	7,858	7,697
Total receivables from broker-dealers and clearing organizations	1,318,584	1,101,449
Liabilities
Due to prime brokers	511,524	354,300
Net equity with futures commission merchants	50,950	47,998
Unsettled trades with clearing organization	118,286	90,021
Securities failed to receive	144,494	73,547
Commissions and fees	1,496	1,575
Total payables to broker-dealers and clearing organizations	826,750	567,441
Outstanding principal balance	$ 134,300	$ 184,600