Fair value as of the balance sheet date of customer securities accepted as collateral by the entity that it has sold or re-pledged to counterparties as collateral.

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4/FIN46(R)-8

-Paragraph B6

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 17

-Subparagraph a(3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 4

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6862952&loc=SL6226653-111729

Reference 4: 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=6862952&loc=SL6224234-111729

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Commitments, Guarantees, and Contingencies (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010	Dec. 31, 2010 Phase Two [Member]	Dec. 31, 2010 Phase Three [Member]	Dec. 31, 2011 Final Phase [Member]	Sep. 30, 2011 Retail Clients [Member]	Sep. 30, 2011 Minimum [Member] Options Clearing Corporation [Member]	Sep. 30, 2011 Minimum [Member] National Securities Clearing Corporation [Member]
Customer-owned securities pledged		$ 109.6
Minimum margin deposit requirements	26.8						48.4	19.9
Auction rate securities, at par, held by retail clients after issuer redemptions and Stifel repurchases						45.7
Issuer redemptions of auction rate securities, at par						58.1
Auction rate securities redemptions				39.2
Stifel repurchases of customer auction rate securties during the year ended December 31, 2010			39.2
Stifel repurchases of customer auction rate securities, at par						92.6
Purchase of auction rate securities from customers, at par					45.3
Commitments to invest in affiliated and unaffiliated investment partnerships	$ 4.1