Commitments, Guarantees, and Contingencies (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Customer-owned securities pledged	$ 67.6	$ 109.6	$ 42.5
Minimum margin deposit requirements	21.3
Purchase of auction rate securities from customers, at par	50.0
Commitments to invest in affiliated and unaffiliated investment partnerships	4.3
Phase Two [Member]
Stifel repurchases of customer auction rate securties during the year ended December 31, 2010		39.2
Phase Three [Member]
Auction rate securities redemptions		39.2
Final Phase [Member]
Purchase of auction rate securities from customers, at par	50.8
Retail Clients [Member]
Auction rate securities, at par, held by retail clients after issuer redemptions and Stifel repurchases	51.3
Issuer redemptions of auction rate securities, at par	54.1
Stifel repurchases of customer auction rate securities, at par	90.9
Minimum [Member] | Options Clearing Corporation [Member]
Minimum margin deposit requirements	42.3
Minimum [Member] | National Securities Clearing Corporation [Member]
Minimum margin deposit requirements	$ 13.8