Collateralized Transactions (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financial instruments owned and pledged
Financial instruments owned and pledged, where counterparty has right to repledge	$ 152,178	$ 143,883
Securities received as collateral:
Securities borrowed	274,815	213,203
Equity securities
Financial instruments owned and pledged
Financial instruments owned and pledged, where counterparty has right to repledge	149,773	128,202
Exchange traded notes
Financial instruments owned and pledged
Financial instruments owned and pledged, where counterparty has right to repledge	$ 2,405	$ 15,681

The fair value as of the balance sheet date of financial instruments and other positions owned by the entity and pledged to counterparties as collateral, including: (1) mortgages, mortgage-backed and asset backed securities; (2) US government and agency obligations; (3) state and municipal government obligations; (4) other sovereign government debt; (5) corporate obligations; (6) corporate equities; (7) principal investments; (8) derivative contracts; and (9) physical commodities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729

Name:	us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant