Commitments and Contingencies - Fixed Maintenance Reserve Payments and Other Commitments (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015
Fixed Maintenance Reserve Payments, Aircraft and Related Flight Equipment [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year	$ 5.7
Unrecorded Unconditional Purchase Obligation, Due in 2016	8.0
Unrecorded Unconditional Purchase Obligation, Due in 2017	7.4
Unrecorded Unconditional Purchase Obligation, Due in 2018	5.8
Unrecorded Unconditional Purchase Obligation, Due in 2019	4.2
Unrecorded Unconditional Purchase Obligation, Due in 2020 and beyond	14.1
Reservation System and Advertising Media [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation, Due in Remainder of Fiscal Year	3.9
Unrecorded Unconditional Purchase Obligation, Due in 2016	3.9
Unrecorded Unconditional Purchase Obligation, Due in 2017	3.9
Unrecorded Unconditional Purchase Obligation, Due in 2018	2.6
Unrecorded Unconditional Purchase Obligation, Due in 2019	0
Unrecorded Unconditional Purchase Obligation, Due in 2020 and beyond	$ 0

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 440

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the remainder of the fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

No definition available.

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