|
Fair Value Measurements and Derivatives - Additional Information (Detail)
|
1 Months Ended | 12 Months Ended | 6 Months Ended | 12 Months Ended | 6 Months Ended | 12 Months Ended | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Feb. 29, 2012
USD ($)
|
Jun. 30, 2013
USD ($)
|
Dec. 31, 2012
USD ($)
|
Sep. 30, 2012
USD ($)
|
Dec. 31, 2011
USD ($)
|
Oct. 31, 2010
Interest Rate Swap [Member]
USD ($)
|
Jun. 30, 2013
Fuel Swaps
Mg
|
Dec. 31, 2012
Fuel Swaps
Mg
|
Jun. 30, 2013
Fuel Swaps
Maximum
|
Dec. 31, 2012
Fuel Swaps
Maximum
|
Jun. 30, 2013
Fuel Collars and Fuel Options
Mg
|
Dec. 31, 2012
Fuel Collars and Fuel Options
Mg
|
Jun. 30, 2013
Fuel Collars and Fuel Options
Maximum
|
Dec. 31, 2012
Fuel Collars and Fuel Options
Maximum
|
Jun. 30, 2013
Foreign Exchange Option
USD ($)
|
Jun. 30, 2013
Foreign Exchange Option
EUR (€)
|
Dec. 31, 2012
Foreign Exchange Option
USD ($)
|
Dec. 31, 2012
Foreign Exchange Option
EUR (€)
|
Dec. 31, 2012
Foreign Exchange Forward
USD ($)
|
Dec. 31, 2012
Foreign Exchange Forward
EUR (€)
|
Jun. 30, 2013
Foreign Currency Collar
USD ($)
|
Jun. 30, 2013
Foreign Currency Collar
EUR (€)
|
Dec. 31, 2012
Foreign Currency Collar
USD ($)
|
Dec. 31, 2012
Foreign Currency Collar
EUR (€)
|
|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ||||||||||||||||||||||||
| Derivative maturing date | Dec. 31, 2015 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2014 | ||||||||||||||||||||
| Projected fuel purchases | 761,000 | 534,000 | 52,000 | 91,000 | ||||||||||||||||||||
| Notional amount of foreign currency derivatives | $ 227,700,000 | € 175,000,000 | $ 521,100,000 | € 395,000,000 | $ 259,900,000 | € 197,000,000 | $ 130,100,000 | € 100,000,000 | $ 131,900,000 | € 100,000,000 | ||||||||||||||
| Loss on maturity of Interest rate swap recognized in Other Income(Expense) | (623,000) | |||||||||||||||||||||||
| Fair value of long-term debt | 3,093,200,000 | 3,106,900,000 | 3,113,900,000 | |||||||||||||||||||||
| Fair value of long-term debt in excess of carrying value | 98,000,000 | 121,500,000 | 75,800,000 | |||||||||||||||||||||
| Business acquisition, purchase price | 7,500,000 | |||||||||||||||||||||||
| Business acquisition, cash paid | 4,000,000 | |||||||||||||||||||||||
| Business acquisition, contingent consideration | 3,500,000 | |||||||||||||||||||||||
| Business acquisition, goodwill and tradenames | $ 8,500,000 | |||||||||||||||||||||||