Fair Value Measurements (Carrying Amounts And Estimated Fair Values Of Other Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Note receivable, Carrying Amount	$ 0.6	$ 0.7
Note receivable, Fair Value	0.7	0.8
Short-term borrowings, Carrying Amount	0.1	2.6
Short-term borrowings, Fair Value	0.1	2.6
3.35% Senior notes, Carrying Amount	249.8	249.7
3.35% Senior notes, Fair Value	262.5	260.2
3.35% Senior Notes Due December 15, 2015 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
3.35% Senior notes, Carrying Amount	$ 249.8	$ 249.7
Interest rate of debt	3.35%