Commitments and Contingent Liabilities - Capital Commitments and Operating Expenditures (Details) - Jun. 30, 2015 $ in Thousands	USD ($) spare_engine_ordered aircraft_purchase_right aircraft_firm_order
Total Committed Expenditures
Remaining months in 2015	$ 114,195
2016	136,737
2017	279,070
2018	449,735
2019	528,881
Thereafter	697,282
Total	2,205,900
Less: Committed Financing for Upcoming Aircraft Deliveries
Remaining months in 2015	48,138
Total	48,138
Net Committed Expenditures
Remaining months in 2015	66,057
2016	136,737
2017	279,070
2018	449,735
2019	528,881
Thereafter	697,282
Total	2,157,762
Capital
Total Committed Expenditures
Remaining months in 2015	79,029
2016	78,018
2017	220,433
2018	397,793
2019	481,519
Thereafter	433,101
Total	$ 1,689,893
Capital | A330-200 aircraft
Commitments and Contingent Liabilities
Number of firm aircraft orders | aircraft_firm_order	1
Number of aircraft purchase rights | aircraft_purchase_right	0
Capital | A330-800neo aircraft
Commitments and Contingent Liabilities
Number of firm aircraft orders | aircraft_firm_order	6
Number of aircraft purchase rights | aircraft_purchase_right	6
Capital | A330-800neo aircraft | Rolls-Royce spare engines
Commitments and Contingent Liabilities
Firm orders, number of spare engines | spare_engine_ordered	2
Capital | A321neo aircraft
Commitments and Contingent Liabilities
Number of firm aircraft orders | aircraft_firm_order	16
Number of aircraft purchase rights | aircraft_purchase_right	9
Capital | A321neo aircraft | Pratt & Whitney spare engines
Commitments and Contingent Liabilities
Firm orders, number of spare engines | spare_engine_ordered	2
Capital | ATR Turboprop
Commitments and Contingent Liabilities
Number of firm aircraft orders | aircraft_firm_order	3
Number of aircraft purchase rights | aircraft_purchase_right	0
Operating
Total Committed Expenditures
Remaining months in 2015	$ 35,166
2016	58,719
2017	58,637
2018	51,942
2019	47,362
Thereafter	264,181
Total	$ 516,007