Commitments, Guarantees, And Contingencies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Customer-owned securities pledged	$ 140.3	$ 80.2
Minimum margin deposit requirements	17.0
Auction rate securities, at par, held by retail clients after issuer redemptions and Stifel repurchases	18.4
Auction rate securities, repurchase period	3 years
Rent expense	60.0	58.6	53.9
Sublease income	0.5	1.9	1.2
Options Clearing Corporation [Member]
Customer-owned securities pledged	109.7
National Securities Clearing Corporation [Member]
Minimum margin deposit requirements	13.2
Minimum [Member]
Minimum margin deposit requirements	$ 52.2