|
Financial Instruments (Details 4) (USD $)
In Millions, unless otherwise specified |
Mar. 31, 2013
|
Dec. 31, 2012
|
|---|---|---|
| Liabilities: | ||
| Fair value of fuel and commodity hedges included in other accrued liabilities | $ 1.8 | $ 1.6 |
|
Fair Value, Measurements, Recurring [Member]
|
||
| Assets: | ||
| Total assets | 109.9 | 107.0 |
| Liabilities: | ||
| Total liabilities | 1.8 | 1.6 |
|
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets (Level 1) [Member]
|
||
| Assets: | ||
| Total assets | 62.3 | 62.8 |
| Liabilities: | ||
| Total liabilities | 0 | 0 |
|
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
|
||
| Assets: | ||
| Total assets | 47.6 | 44.2 |
| Liabilities: | ||
| Total liabilities | 1.8 | 1.6 |
|
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
|
||
| Assets: | ||
| Total assets | 0 | 0 |
| Liabilities: | ||
| Total liabilities | 0 | 0 |
|
Fair Value, Measurements, Recurring [Member] | Commodity hedges [Member]
|
||
| Assets: | ||
| Other current assets | 0.4 | 1.0 |
| Liabilities: | ||
| Fair value of fuel and commodity hedges included in other accrued liabilities | 1.7 | 1.2 |
|
Fair Value, Measurements, Recurring [Member] | Commodity hedges [Member] | Quoted Prices in Active Markets (Level 1) [Member]
|
||
| Assets: | ||
| Other current assets | 0 | 0 |
| Liabilities: | ||
| Fair value of fuel and commodity hedges included in other accrued liabilities | 0 | 0 |
|
Fair Value, Measurements, Recurring [Member] | Commodity hedges [Member] | Significant Other Observable Inputs (Level 2) [Member]
|
||
| Assets: | ||
| Other current assets | 0.4 | 1.0 |
| Liabilities: | ||
| Fair value of fuel and commodity hedges included in other accrued liabilities | 1.7 | 1.2 |
|
Fair Value, Measurements, Recurring [Member] | Commodity hedges [Member] | Significant Unobservable Inputs (Level 3) [Member]
|
||
| Assets: | ||
| Other current assets | 0 | 0 |
| Liabilities: | ||
| Fair value of fuel and commodity hedges included in other accrued liabilities | 0 | 0 |
|
Fair Value, Measurements, Recurring [Member] | Fuel hedges [Member]
|
||
| Assets: | ||
| Other current assets | 5.0 | 3.1 |
| Liabilities: | ||
| Fair value of fuel and commodity hedges included in other accrued liabilities | 0.1 | 0.4 |
|
Fair Value, Measurements, Recurring [Member] | Fuel hedges [Member] | Quoted Prices in Active Markets (Level 1) [Member]
|
||
| Assets: | ||
| Other current assets | 0 | 0 |
| Liabilities: | ||
| Fair value of fuel and commodity hedges included in other accrued liabilities | 0 | 0 |
|
Fair Value, Measurements, Recurring [Member] | Fuel hedges [Member] | Significant Other Observable Inputs (Level 2) [Member]
|
||
| Assets: | ||
| Other current assets | 5.0 | 3.1 |
| Liabilities: | ||
| Fair value of fuel and commodity hedges included in other accrued liabilities | 0.1 | 0.4 |
|
Fair Value, Measurements, Recurring [Member] | Fuel hedges [Member] | Significant Unobservable Inputs (Level 3) [Member]
|
||
| Assets: | ||
| Other current assets | 0 | 0 |
| Liabilities: | ||
| Fair value of fuel and commodity hedges included in other accrued liabilities | 0 | 0 |
|
Fair Value, Measurements, Recurring [Member] | Money market mutual funds [Member]
|
||
| Assets: | ||
| Available-for-sale securities | 62.3 | 62.8 |
|
Fair Value, Measurements, Recurring [Member] | Money market mutual funds [Member] | Quoted Prices in Active Markets (Level 1) [Member]
|
||
| Assets: | ||
| Available-for-sale securities | 62.3 | 62.8 |
|
Fair Value, Measurements, Recurring [Member] | Money market mutual funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
|
||
| Assets: | ||
| Available-for-sale securities | 0 | 0 |
|
Fair Value, Measurements, Recurring [Member] | Money market mutual funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
|
||
| Assets: | ||
| Available-for-sale securities | 0 | 0 |
|
Fair Value, Measurements, Recurring [Member] | Bonds [Member]
|
||
| Assets: | ||
| Available-for-sale securities | 42.2 | 40.1 |
|
Fair Value, Measurements, Recurring [Member] | Bonds [Member] | Quoted Prices in Active Markets (Level 1) [Member]
|
||
| Assets: | ||
| Available-for-sale securities | 0 | 0 |
|
Fair Value, Measurements, Recurring [Member] | Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member]
|
||
| Assets: | ||
| Available-for-sale securities | 42.2 | 40.1 |
|
Fair Value, Measurements, Recurring [Member] | Bonds [Member] | Significant Unobservable Inputs (Level 3) [Member]
|
||
| Assets: | ||
| Available-for-sale securities | $ 0 | $ 0 |