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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
3 Months Ended 1 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Feb. 29, 2012
Feb. 29, 2012
Performance Shares
Significant Accounting Policies [Line Items]        
Percentage of target number of performance shares     200.00%  
Performance shares issued       327,240
Gross amount of port costs included in passenger ticket revenues $ 113.1 $ 95.7