Commitments and Contingencies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014
Capital Addition Purchase Commitments [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Aircraft Purchase Commitments, Total	$ 8,520
B-737-900ER [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation, Minimum Quantity Required	73
A321-200 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation, Minimum Quantity Required	45
B-787-8 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation, Minimum Quantity Required	18
CRJ-900 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation, Minimum Quantity Required	6
A330-300 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Unrecorded Unconditional Purchase Obligation, Minimum Quantity Required	10
B-717-200 [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
Other Aircraft Commitments	43