|
Fair Value Measurements and Derivatives - Additional Information (Detail)
In Millions, unless otherwise specified |
9 Months Ended | 9 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Sep. 30, 2013
USD ($)
|
Dec. 31, 2012
USD ($)
|
Sep. 30, 2013
Fuel Swaps
Mg
|
Sep. 30, 2013
Fuel Swaps
Maximum
|
Sep. 30, 2013
Fuel Collars and Fuel Options
Mg
|
Sep. 30, 2013
Fuel Collars and Fuel Options
Maximum
|
Sep. 30, 2013
Foreign Exchange Option
USD ($)
|
Sep. 30, 2013
Foreign Exchange Option
EUR (€)
|
Sep. 30, 2013
Foreign Currency Collar
USD ($)
|
Sep. 30, 2013
Foreign Currency Collar
EUR (€)
|
Sep. 30, 2013
Interest Rate Swap
USD ($)
|
|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |||||||||||
| Derivative maturing date | Dec. 31, 2016 | Dec. 31, 2014 | |||||||||
| Projected fuel purchases | 745,000 | 43,000 | |||||||||
| Notional amount of derivatives | $ 236.7 | € 175.0 | $ 135.3 | € 100.0 | $ 705.8 | ||||||
| Fair value of long-term debt | 3,105.0 | 3,106.9 | |||||||||
| Fair value of long-term debt in excess of carrying value | $ 8.0 | $ 121.5 | |||||||||