Collateralized Transactions - Assets Pledged (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Repurchase Agreement Counterparty [Line Items]
Financial instruments owned, at fair value, pledged to counterparties that have the right to deliver or repledge	$ 1,634,979	$ 1,640,145
Right to deliver or repledge
Repurchase Agreement Counterparty [Line Items]
Financial instruments owned, at fair value, pledged to counterparties that have the right to deliver or repledge	314,720	324,146
Not having the right to deliver or repledge
Repurchase Agreement Counterparty [Line Items]
Financial instruments owned, at fair value, pledged to counterparties that do not have the right to deliver or repledge	$ 1,291,979	$ 1,027,847

The fair value as of the balance sheet date of financial instruments and other positions owned by the entity 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. Excludes financial instruments and other positions owned and pledged as collateral to counterparties.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 320
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=35711157&loc=d3e42546-110969

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- Definition

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.

+ References

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

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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