|
Fair Value Measurements and Derivatives - Additional Information (Detail)
In Millions, unless otherwise specified |
3 Months Ended | 3 Months Ended | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Mar. 31, 2013
USD ($)
|
Dec. 31, 2012
USD ($)
|
Mar. 31, 2013
Fuel Swaps
Mg
|
Mar. 31, 2013
Fuel Swaps
Maximum
|
Mar. 31, 2013
Fuel Collars and Fuel Options
Mg
|
Mar. 31, 2013
Fuel Collars and Fuel Options
Maximum
|
Mar. 31, 2013
Foreign Exchange Option
USD ($)
|
Mar. 31, 2013
Foreign Exchange Option
EUR (€)
|
Mar. 31, 2013
Foreign Exchange Forward
USD ($)
|
Mar. 31, 2013
Foreign Exchange Forward
EUR (€)
|
Mar. 31, 2013
Foreign Currency Collar
USD ($)
|
Mar. 31, 2013
Foreign Currency Collar
EUR (€)
|
|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||||||||||||
| Derivative maturing date | Dec. 31, 2015 | Dec. 31, 2014 | ||||||||||
| Projected fuel purchases | 484,000 | 61,000 | ||||||||||
| Notional amount of foreign currency derivatives | $ 224.3 | € 175.0 | $ 598.6 | € 467.0 | $ 128.2 | € 100.0 | ||||||
| Fair value of long-term debt | 2,747.8 | 3,106.9 | ||||||||||
| Fair value of long-term debt in excess of carrying value | $ 109.5 | $ 121.5 | ||||||||||