Segment Information (Financial Information With Respect To Business Segments And Discontinued Operations Related To Identifiable Assets) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Discontinued operations	$ 126.5	$ 121.2
Total assets	12,913.4	12,598.6
U.S. Companies [Member]
Segment Reporting Information [Line Items]
Identifiable assets	8,484.7	8,471.6
Chaucer [Member]
Segment Reporting Information [Line Items]
Identifiable assets	$ 4,302.2	$ 4,005.8