Leases and Prepaid Maintenance Deposits - Fixed Maintenance Reserve Payments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Leases And Prepaid Maintenance Deposits [Abstract]
Estimated fixed maintenance reserve payments, 2014	$ 7.4
Estimated fixed maintenance reserve payments, 2015	7.6
Estimated fixed maintenance reserve payments, 2016	8.0
Estimated fixed maintenance reserve payments, 2017	7.4
Estimated fixed maintenance reserve payments, 2018	5.8
Estimated fixed maintenance reserve payments, 2019 and beyond	$ 18.4

Fixed Maintenance Reserve Payments, Future Estimated Payments Due, Due After Five Years

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Fixed Maintenance Reserve Payments, Future Estimated Payments Due, Due Within Five Years

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Fixed Maintenance Reserve Payments, Future Estimated Payments Due, Due Within Four Years

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Fixed Maintenance Reserve Payments, Future Estimated Payments Due, Due Within Three Years

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Fixed Maintenance Reserve Payments, Future Estimated Payments Due, Due Within Two Years

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Fixed Maintenance Reserve Payments, Future Estimated Payments Due, Within Twelve Months

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