Collateralized Transactions - Schedule of Gross Amount Recognized Liabilities (Details) $ in Thousands	Sep. 30, 2015 USD ($)
Securities loaned:
Gross amount of recognized liabilities for repurchase agreements and securities loaned	$ 1,076,792
Maturity Overnight and Open [Member]
Securities loaned:
Gross amount of recognized liabilities for repurchase agreements and securities loaned	1,076,792
Maturity Less than 30 Days [Member]
Securities loaned:
Gross amount of recognized liabilities for repurchase agreements and securities loaned	0
US Treasury and Government [Member]
Repurchase agreements:
U.S. Treasury and agency securities	867,667
US Treasury and Government [Member] \| Maturity Overnight and Open [Member]
Repurchase agreements:
U.S. Treasury and agency securities	867,667
US Treasury and Government [Member] \| Maturity Less than 30 Days [Member]
Repurchase agreements:
U.S. Treasury and agency securities	0
Equity Securities [Member]
Securities loaned:
Equity securities	209,125
Equity Securities [Member] \| Maturity Overnight and Open [Member]
Securities loaned:
Equity securities	209,125
Equity Securities [Member] \| Maturity Less than 30 Days [Member]
Securities loaned:
Equity securities	$ 0

Amount, before effects of master netting arrangements, of funds outstanding borrowed in the form of a financial asset repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same financial asset at a date certain for a specified price. Includes repurchase-to-maturity transactions and liabilities not subject to a master netting arrangement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 7

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=55761124&loc=SL34722452-111729

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- Definition

Amount, before effects of master netting arrangements, of securities borrowed from entities in exchange for collateral. Includes assets not subject to a master netting arrangement and elected not to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

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Amount, before effects of master netting arrangements, of financial assets loaned to entities in exchange for collateral. Includes liabilities not subject to a master netting arrangement and financial assets transferred other than securities that qualify as secured borrowings.

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