Collateralized Transactions - Schedule of Gross Amounts and Offsetting Amounts of Reverse Repurchase Agreements, Repurchase Agreements, Securities Borrowed and Securities Lending Transactions (Details) - USD ($) $ in Thousands	Dec. 31, 2015		Dec. 31, 2014
Reverse repurchase agreements
Gross Amounts of Recognized Assets	$ 282,042		$ 314,266
Gross Amounts Offset on the Balance Sheet	(75,543)		(62,660)
Net Amounts of Assets Presented on the Balance Sheet	206,499		251,606
Financial Instruments	(203,266)		(250,000)
Cash Collateral Received	0		0
Net Amount	3,233		1,606
Securities borrowed
Gross Amounts of Recognized Assets	224,672	[1]	242,172	[2]
Gross Amounts Offset on the Balance Sheet	0	[1]	0	[2]
Net Amounts of Assets Presented on the Balance Sheet	224,672	[1]	242,172	[2]
Financial Instruments	(219,099)	[1]	(234,376)	[2]
Cash Collateral Received	0	[1]	0	[2]
Net Amount	5,573	[1]	7,796	[2]
Total
Gross Amounts of Recognized Assets	506,714		556,438
Gross Amounts Offset on the Balance Sheet	(75,543)		(62,660)
Net Amounts of Assets Presented on the Balance Sheet	431,171		493,778
Financial Instruments	(422,365)		(484,376)
Cash Collateral Received	0		0
Net Amount	8,806		9,402
Repurchase agreements
Gross Amounts of Recognized Liabilities	726,988		750,100
Gross Amounts Offset on the Balance Sheet	(75,543)		(62,660)
Net Amounts of Liabilities Presented on the Balance Sheet	651,445		687,440
Financial Instruments	(645,498)		(686,119)
Cash Collateral Pledged	0		0
Net Amount	5,947		1,321
Securities loaned
Gross Amounts of Recognized Liabilities	130,658	[3]	137,892	[4]
Gross Amounts Offset on the Balance Sheet	0	[3]	0	[4]
Net Amounts of Liabilities Presented on the Balance Sheet	130,658	[3]	137,892	[4]
Financial Instruments	(122,650)	[3]	(132,258)	[4]
Cash Collateral Pledged	0	[3]	0	[4]
Net Amount	8,008	[3]	5,634	[4]
Total
Gross Amounts of Recognized Liabilities	857,646		887,992
Gross Amounts Offset on the Balance Sheet	(75,543)		(62,660)
Net Amounts of Liabilities Presented on the Balance Sheet	782,103		825,332
Financial Instruments	(768,148)		(818,377)
Cash Collateral Pledged	0		0
Net Amount	$ 13,955		$ 6,955

[1] Included in receivable from brokers, dealers and clearing organizations on the consolidated balance sheet.

[2] Included in receivable from brokers, dealers and clearing organizations on the consolidated balance sheet.

[3] Included in payable to brokers, dealers and clearing organizations on the consolidated balance sheet.

[4] Included in payable to brokers, dealers and clearing organizations on the consolidated balance sheet.