Collateralized Transactions (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial instruments owned and pledged
Financial instruments owned and pledged, where counterparty has right to repledge	$ 595,043	$ 143,883
Securities received as collateral:
Securities borrowed	1,415,793	213,203
Total amounts related to collateralized transactions	1,415,793	213,203
Equity securities
Financial instruments owned and pledged
Financial instruments owned and pledged, where counterparty has right to repledge	586,251	128,202
US and non-US government obligations
Financial instruments owned and pledged
Financial instruments owned and pledged, where counterparty has right to repledge	99
Exchange traded notes
Financial instruments owned and pledged
Financial instruments owned and pledged, where counterparty has right to repledge	$ 8,693	$ 15,681

The total of collateralized agreements including securities purchased under agreements to resell (repos), borrowed securities, and secured demand notes.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(m)(2)(i)(A))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 10
-Section 05
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=64836671&loc=d3e93640-111703

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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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