Fair Value Measurements (Details) (USD $) | Mar. 31, 2014 | Dec. 31, 2013 | Mar. 31, 2013 |
In Thousands, unless otherwise specified |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Assets (liabilities) at fair value | ' | | $0 | | ' | |
Investments & other assets, net | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | -1,936 | [1] | ' | | ' | |
Assets (Liabilties) at Fair Value | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Assets (liabilities) at fair value | -4,627 | | -3,781 | | 3,038 | |
Assets (Liabilties) at Fair Value | Other current assets | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Net amount of recorded assets | ' | | ' | | 3,103 | |
Assets (Liabilties) at Fair Value | Other current assets | Bunker fuel forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | ' | | ' | | 5,219 | |
Assets (Liabilties) at Fair Value | Other current assets | 30-day euro forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | ' | | -186 | |
Assets (Liabilties) at Fair Value | Other current assets | Designated as cash flow hedges | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | ' | | ' | | 2,078 | [1] |
Gross amounts offset in the balance sheets | ' | | ' | | -2,935 | [1] |
Assets (Liabilties) at Fair Value | Other current assets | Derivatives not designated as hedging instruments | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | ' | | ' | | 187 | [2] |
Gross amounts offset in the balance sheets | ' | | ' | | -1,260 | [2] |
Assets (Liabilties) at Fair Value | Investments & other assets, net | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Net amount of recorded assets | 417 | | 633 | | 3,250 | |
Assets (Liabilties) at Fair Value | Investments & other assets, net | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | 2,146 | [1] | ' | | ' | |
Gross amounts offset in the balance sheets | -1,936 | [1] | ' | | ' | |
Assets (Liabilties) at Fair Value | Investments & other assets, net | Bunker fuel forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | 373 | | 953 | | ' | |
Gross amounts offset in the balance sheets | -166 | | -100 | | ' | |
Assets (Liabilties) at Fair Value | Investments & other assets, net | Designated as cash flow hedges | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | ' | | ' | | 3,024 | [1] |
Gross amounts offset in the balance sheets | ' | | ' | | -632 | [1] |
Assets (Liabilties) at Fair Value | Investments & other assets, net | Designated as cash flow hedges | Bunker fuel forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | ' | | ' | | 1,679 | |
Gross amounts offset in the balance sheets | ' | | ' | | -821 | |
Assets (Liabilties) at Fair Value | Accrued liabilities | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Net amount of recorded liabilities | -5,044 | | -4,317 | | -3,315 | |
Assets (Liabilties) at Fair Value | Accrued liabilities | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | 2,937 | [1] | 1,250 | [1] | ' | |
Gross amounts of recognized liabilities | -6,978 | [1] | -5,947 | [1] | ' | |
Assets (Liabilties) at Fair Value | Accrued liabilities | Bunker fuel forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | 643 | | ' | |
Gross amounts offset in the balance sheets | 317 | | 778 | | ' | |
Gross amounts of recognized liabilities | -1,158 | | ' | | ' | |
Assets (Liabilties) at Fair Value | Accrued liabilities | 30-day euro forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | 245 | | ' | |
Gross amounts of recognized liabilities | -162 | | ' | | ' | |
Assets (Liabilties) at Fair Value | Accrued liabilities | Designated as cash flow hedges | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | ' | | 1,456 | [1] |
Gross amounts of recognized liabilities | ' | | ' | | -6,116 | [1] |
Assets (Liabilties) at Fair Value | Accrued liabilities | Designated as cash flow hedges | Bunker fuel forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | ' | | 1,544 | |
Assets (Liabilties) at Fair Value | Accrued liabilities | Derivatives not designated as hedging instruments | 30-day euro forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized liabilities | ' | | ' | | -199 | |
Assets (Liabilties) at Fair Value | Other liabilities | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Total financial assets and liabilities at fair value | ' | | -97 | | ' | |
Level 2 | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Assets (liabilities) at fair value | -4,627 | | -3,781 | | 3,038 | |
Level 2 | Other current assets | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Net amount of recorded assets | ' | | ' | | 3,103 | |
Level 2 | Other current assets | Bunker fuel forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | ' | | ' | | 5,219 | |
Level 2 | Other current assets | 30-day euro forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | ' | | -186 | |
Level 2 | Other current assets | Designated as cash flow hedges | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | ' | | ' | | 2,078 | [1] |
Gross amounts offset in the balance sheets | ' | | ' | | -2,935 | [1] |
Level 2 | Other current assets | Derivatives not designated as hedging instruments | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | ' | | ' | | 187 | [2] |
Gross amounts offset in the balance sheets | ' | | ' | | -1,260 | [2] |
Level 2 | Investments & other assets, net | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Net amount of recorded assets | 417 | | 633 | | 3,250 | |
Level 2 | Investments & other assets, net | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | 2,146 | [1] | ' | | ' | |
Level 2 | Investments & other assets, net | Bunker fuel forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | 373 | | 953 | | ' | |
Gross amounts offset in the balance sheets | -166 | | -100 | | ' | |
Level 2 | Investments & other assets, net | Designated as cash flow hedges | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | ' | | ' | | 3,024 | [1] |
Gross amounts offset in the balance sheets | ' | | ' | | -632 | [1] |
Level 2 | Investments & other assets, net | Designated as cash flow hedges | Bunker fuel forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized assets | ' | | ' | | 1,679 | |
Gross amounts offset in the balance sheets | ' | | ' | | -821 | |
Level 2 | Accrued liabilities | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Net amount of recorded liabilities | -5,044 | | -4,317 | | -3,315 | |
Level 2 | Accrued liabilities | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | 2,937 | [1] | 1,250 | [1] | ' | |
Gross amounts of recognized liabilities | -6,978 | [1] | -5,947 | [1] | ' | |
Level 2 | Accrued liabilities | Bunker fuel forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | 317 | | 778 | | ' | |
Gross amounts of recognized liabilities | -1,158 | | 643 | | ' | |
Level 2 | Accrued liabilities | 30-day euro forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | 245 | | ' | |
Gross amounts of recognized liabilities | -162 | | ' | | ' | |
Level 2 | Accrued liabilities | Designated as cash flow hedges | Currency hedge portfolio | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | ' | | 1,456 | [1] |
Gross amounts of recognized liabilities | ' | | ' | | -6,116 | [1] |
Level 2 | Accrued liabilities | Designated as cash flow hedges | Bunker fuel forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | ' | | 1,544 | |
Level 2 | Accrued liabilities | Derivatives not designated as hedging instruments | 30-day euro forward contracts | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized liabilities | ' | | ' | | -199 | |
Level 2 | Other liabilities | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Total financial assets and liabilities at fair value | ' | | -97 | | ' | |
Currency hedge portfolio [Member] | Assets (Liabilties) at Fair Value | Gross liabilties included in Other liabilities [Member] | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized liabilities | ' | | -930 | [1] | ' | |
Currency hedge portfolio [Member] | Assets (Liabilties) at Fair Value | Gross Liabilities Included in Investments & other assets [Member] | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | -220 | [1] | ' | |
Currency hedge portfolio [Member] | Assets (Liabilties) at Fair Value | Gross Assets Included in Other Liabilities [Member] | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | 833 | [1] | ' | |
Currency hedge portfolio [Member] | Level 2 | Gross liabilties included in Other liabilities [Member] | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts of recognized liabilities | ' | | -930 | [1] | ' | |
Currency hedge portfolio [Member] | Level 2 | Gross Liabilities Included in Investments & other assets [Member] | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | -220 | [1] | ' | |
Currency hedge portfolio [Member] | Level 2 | Gross Assets Included in Other Liabilities [Member] | ' | | ' | | ' | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | ' | | ' | | ' | |
Gross amounts offset in the balance sheets | ' | | $833 | [1] | ' | |
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