Commitments and Contingencies - Fixed Maintenance Reserve Payments and Other Commitments (Details) $ in Millions	Mar. 31, 2017 USD ($)
Fixed Maintenance Reserve Payments, Aircraft and Related Flight Equipment [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Committed expenditures, remainder of 2017	$ 5.8
Committed expenditures, 2018	7.0
Committed expenditures, 2019	5.7
Committed expenditures, 2020	5.4
Committed expenditures, 2021	5.5
Committed expenditures, 2022 and beyond	17.7
Non-aircraft Related Commitments [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Committed expenditures, remainder of 2017	4.7
Committed expenditures, 2018	4.4
Committed expenditures, 2019	0.8
Committed expenditures, 2020	0.5
Committed expenditures, 2021	0.1
Committed expenditures, 2022 and beyond	$ 0.0

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=73718637&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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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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