Commitments, Guarantees, And Contingencies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
CommitmentsOutstandingtoBusinessDevelopmentCorporations	$ 63.3
CommitmentsOutstanding	76.0
Customer-owned securities pledged	255.5	140.3
Minimum margin deposit requirements	27.4
Auction rate securities, at par, held by retail clients after issuer redemptions and Stifel repurchases	18.3
Auction rate securities, repurchase period	3 years
Options Clearing Corporation [Member]
Customer-owned securities pledged	103.7
National Securities Clearing Corporation [Member]
Minimum margin deposit requirements	20.9
Minimum [Member]
Minimum margin deposit requirements	$ 34.4