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Consolidated Balance Sheets (Parenthetical) (USD $)
In Millions, unless otherwise specified |
Dec. 31, 2011
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Dec. 31, 2010
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|---|---|---|
| Accumulated depreciation on vessels and equipment | $ 391.6 | $ 317.1 |
| Common stock, shares authorized | 300 | 300 |
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Class A [Member]
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| Common stock, shares issued | 49.4 | 39.5 |
| Common stock, shares outstanding | 49.4 | 39.5 |
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Class B [Member]
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| Common stock, shares issued | 12.5 | 12.5 |
| Common stock, shares outstanding | 12.5 | 12.5 |
| X | ||||||||||
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- Definition
The cumulative amount of depreciation, depletion and amortization (related to property, plant and equipment, but not including land) that has been recognized in the income statement. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The maximum number of common shares permitted to be issued by an entity's charter and bylaws. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Total number of shares of common stock held by shareholders. May be all or portion of the number of common shares authorized. These shares represent the ownership interest of the common shareholders. Shares outstanding equals shares issued minus shares held in treasury and other adjustments, if any. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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