Commitments and Contingencies - Commitments (Details) ft² in Thousands, $ in Millions	1 Months Ended
	Sep. 30, 2015 ft² a extension_option	Jul. 31, 2015 USD ($) aircraft seat	Sep. 30, 2016 USD ($)
Hangar Facility [Member] | Operating Lease [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Area of land, hangar site | a	10
Area of hangar facility | ft²	126
Operating lease, initial term	30 years
Operating lease, number of extension options | extension_option	2
Operating lease, extension term	10 years
Estimated future project costs | $			$ 32.0
Airbus [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Costs to reconfigure aircraft seating | $		$ 0.6
Airbus [Member] | A320 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircraft reconfigured for increased seating capacity | aircraft		40
Airbus [Member] | A320 [Member] | Minimum [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircraft seats | seat		178
Airbus [Member] | A320 [Member] | Maximum [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircraft seats | seat		182