Commitments and Contingencies - Aircraft Contractual Purchase Commitments (Details)	Jun. 30, 2014 aircraft
Long-term Purchase Commitment [Line Items]
Future Aircraft To Be Received, Remainder of FIscal Year	8
Future Aircraft To Be Received, in Two Years	15
Future Aircraft To Be Received, in Three Years	16
Future Aircraft To Be Received, in Four Years	18
Future Aircraft To Be Received, in Five Years	13
Future Aircraft To Be Received, in Six Years	13
Future Aircraft To Be Received, in Seven Years	13
Future Aircraft To Be Received, in Eight Years	18
Future Aircraft To Be Received	114
Airbus [Member] | Airbus 320 [Member]
Long-term Purchase Commitment [Line Items]
Future Aircraft To Be Received, Remainder of FIscal Year	8
Future Aircraft To Be Received, in Two Years	8
Future Aircraft To Be Received, in Three Years	3
Future Aircraft To Be Received, in Four Years	8
Future Aircraft To Be Received, in Five Years	2
Future Aircraft To Be Received	29
Airbus [Member] | Airbus A320 NEO [Member]
Long-term Purchase Commitment [Line Items]
Future Aircraft To Be Received, in Five Years	6
Future Aircraft To Be Received, in Six Years	3
Future Aircraft To Be Received, in Seven Years	13
Future Aircraft To Be Received, in Eight Years	18
Future Aircraft To Be Received	40
Airbus [Member] | Airbus A321 [Member]
Long-term Purchase Commitment [Line Items]
Future Aircraft To Be Received, in Two Years	6
Future Aircraft To Be Received, in Three Years	9
Future Aircraft To Be Received, in Four Years	10
Future Aircraft To Be Received, in Five Years	5
Future Aircraft To Be Received	30
Airbus [Member] | Airbus A321 NEO [Member]
Long-term Purchase Commitment [Line Items]
Future Aircraft To Be Received, in Six Years	10
Future Aircraft To Be Received	10
Third Party Lessor [Member] | Airbus A320 NEO [Member]
Long-term Purchase Commitment [Line Items]
Future Aircraft To Be Received, in Two Years	1
Future Aircraft To Be Received, in Three Years	4
Future Aircraft To Be Received	5