Commitments, Guarantees, and Contingencies (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Customer-owned securities pledged		$ 109.6
Minimum margin deposit requirements	14.7
Purchase of auction rate securities from customers, at par	36.0
Commitments to invest in affiliated and unaffiliated investment partnerships	4.0
Minimum [Member] \| Options Clearing Corporation [Member]
Minimum margin deposit requirements	36.2
Minimum [Member] \| National Securities Clearing Corporation [Member]
Minimum margin deposit requirements	8.7
Phase Three [Member]
Auction rate securities redemptions		$ 39.2

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)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

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-Name Statement of Financial Accounting Standard (FAS)

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-Paragraph 17

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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