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Fair Value Measurements and Derivatives - Additional Information (Detail)
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1 Months Ended | 9 Months Ended | 12 Months Ended | 9 Months Ended | 12 Months Ended | 12 Months Ended | |||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Feb. 29, 2012
USD ($)
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Sep. 30, 2013
USD ($)
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Dec. 31, 2012
USD ($)
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Sep. 30, 2012
USD ($)
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Dec. 31, 2011
USD ($)
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Sep. 30, 2013
Fuel Swaps
Mg
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Dec. 31, 2012
Fuel Swaps
Mg
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Sep. 30, 2013
Fuel Swaps
Maximum
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Dec. 31, 2012
Fuel Swaps
Maximum
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Sep. 30, 2013
Fuel Collars and Fuel Options
Mg
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Dec. 31, 2012
Fuel Collars and Fuel Options
Mg
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Sep. 30, 2013
Fuel Collars and Fuel Options
Maximum
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Dec. 31, 2012
Fuel Collars and Fuel Options
Maximum
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Sep. 30, 2013
Foreign Exchange Option
USD ($)
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Sep. 30, 2013
Foreign Exchange Option
EUR (€)
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Dec. 31, 2012
Foreign Exchange Option
USD ($)
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Dec. 31, 2012
Foreign Exchange Option
EUR (€)
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Dec. 31, 2012
Foreign Exchange Forward
USD ($)
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Dec. 31, 2012
Foreign Exchange Forward
EUR (€)
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Sep. 30, 2013
Foreign Currency Collar
USD ($)
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Sep. 30, 2013
Foreign Currency Collar
EUR (€)
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Dec. 31, 2012
Foreign Currency Collar
USD ($)
|
Dec. 31, 2012
Foreign Currency Collar
EUR (€)
|
Oct. 31, 2010
Interest Rate Swap
USD ($)
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Sep. 30, 2013
Interest Rate Swap
USD ($)
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| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | |||||||||||||||||||||||||
| Derivative maturing date | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2014 | |||||||||||||||||||||
| Projected fuel purchases | 745,000 | 534,000 | 43,000 | 91,000 | |||||||||||||||||||||
| Notional amount of derivatives | $ 236,700,000 | € 175,000,000 | $ 521,100,000 | € 395,000,000 | $ 259,900,000 | € 197,000,000 | $ 135,300,000 | € 100,000,000 | $ 131,900,000 | € 100,000,000 | $ 705,800,000 | ||||||||||||||
| Loss on maturity of Interest rate swap recognized in Other Income(Expense) | (623,000) | ||||||||||||||||||||||||
| Fair value of long-term debt | 3,105,000,000 | 3,106,900,000 | 3,113,900,000 | ||||||||||||||||||||||
| Fair value of long-term debt in excess of carrying value | 8,000,000 | 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 | ||||||||||||||||||||||||