Receivable from and Payable to Brokers, Dealers and Clearing Organizations (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Receivable:
Clearing organizations and other	$ 505,789	$ 1,073,480
Financial instruments purchased under agreement to resell	65,433	21,545
Securities failed to deliver	109,989	93,808
Total Receivable	681,211	1,188,833
Payable:
Clearing organizations and other	240,985	350,627
Securities failed to receive	32,820	325,462
Total Payable	$ 273,805	$ 676,089