|
Fair Value Measurements (Schedule Of Carrying Values And Estimated Fair Values Of Debt Instruments) (Details) (USD $)
In Millions, unless otherwise specified |
Mar. 31, 2011
|
Dec. 31, 2010
|
|---|---|---|
|
Carrying Value [Member]
|
||
| Debt Instrument [Line Items] | ||
| 4.70% Senior Notes | $ 1,470.5 | |
| 3.25% Senior Notes | 992.4 | |
| 7.20% Debentures | 148.9 | 148.9 |
| 6.36% Bonds, including current maturities | 63.4 | 63.4 |
| 4.65% Bonds, including current maturities | 45.0 | 45.0 |
|
Estimate Fair Value [Member]
|
||
| Debt Instrument [Line Items] | ||
| 4.70% Senior Notes | 1,488.9 | |
| 3.25% Senior Notes | 1,001.1 | |
| 7.20% Debentures | 168.4 | 165.0 |
| 6.36% Bonds, including current maturities | 70.8 | 71.9 |
| 4.65% Bonds, including current maturities | $ 50.0 | $ 50.6 |