Fair Value (Carrying And Estimated Fair Values by Level Of Financial Instruments Not Recorded At Fair Value On Consolidated Balance Sheet) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other invested assets, long-term	$ 1,691.8	$ 1,542.6
Short-term borrowings	100.0
Convertible debentures	972.3
Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other invested assets, long-term	1,691.8	1,542.6
Short-term borrowings	100.0	400.0
Commercial paper	425.8	379.2
Notes	13,765.2	12,746.4
Convertible debentures	972.3	966.0
Level I [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other invested assets, long-term	0	0
Short-term borrowings	0	0
Commercial paper	0	0
Notes	0	0
Convertible debentures	0	0
Level II [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other invested assets, long-term	0	0
Short-term borrowings	100.0	400.0
Commercial paper	425.8	379.2
Notes	14,396.1	13,014.3
Convertible debentures	2,470.3	2,030.6
Level III [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other invested assets, long-term	1,691.8	1,542.6
Short-term borrowings	0	0
Commercial paper	0	0
Notes	0	0
Convertible debentures	0	0
Total [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other invested assets, long-term	1,691.8	1,542.6
Short-term borrowings	100.0	400.0
Commercial paper	425.8	379.2
Notes	14,396.1	13,014.3
Convertible debentures	$ 2,470.3	$ 2,030.6