Commitments and Contingencies (Details) $ in Thousands		1 Months Ended	6 Months Ended
	Aug. 09, 2018 lease	Aug. 31, 2018 aircraft	Jun. 30, 2018 USD ($) item aircraft	Dec. 31, 2017 USD ($)
Commitments to acquire aircraft
Minimum aircraft delivery delays that could trigger lessee cancellation clauses (in years)			1 year
Lease contracts, subject to cancellation | lease	0
Commitments for the acquisition of the aircraft and other equipment
2018 | $			$ 2,465,306
2019 | $			6,151,512
2020 | $			5,493,536
2021 | $			5,808,153
2022 | $			5,210,440
Thereafter | $			2,714,769
Total | $			$ 27,843,716
Aircrafts
Commitments to acquire aircraft
2018			25
2019			84
2020			72
2021			78
2022			77
Thereafter			55
Total			391
Commitments for the acquisition of the aircraft and other equipment
Total | $			$ 1,600,000	$ 1,600,000
Airbus A321-200
Commitments to acquire aircraft
2018			2
Total			2
Airbus A320/321neo
Commitments to acquire aircraft
2018			9
2019			36
2020			27
2021			22
2022			25
Thereafter			25
Total			144
Number of long-range variants			55
Airbus A330-900neo
Commitments to acquire aircraft
2018			5
2019			5
2020			4
2021			7
2022			6
Thereafter			2
Total			29
Airbus A350-900/1000
Commitments to acquire aircraft
2018			1
2019			4
2020			2
2021			5
2022			3
Total			15
Boeing 737-7/8/9 MAX
Commitments to acquire aircraft
2018			4
2019			27
2020			29
2021			36
2022			34
Thereafter			28
Total			158
Boeing 787-9/10
Commitments to acquire aircraft
2018			4
2019			12
2020			10
2021			8
2022			9
Total			43
Boeing 787-9 Aircraft
Commitments to acquire aircraft
Total | aircraft		3
Number of aircraft commitments that are included in order book total | aircraft		3
Airbus A350-1000 | Maximum
Commitments for the acquisition of the aircraft and other equipment
Aircraft to be acquired under non-binding commitment | aircraft			5
Boeing Aircraft | Maximum
Commitments to acquire aircraft
Total | aircraft		78
Boeing 737-8 MAX Aircraft
Commitments to acquire aircraft
Total | aircraft		75
Number of aircraft commitments that are included in order book total | aircraft		30
Boeing 737-8 MAX Aircraft | Maximum
Commitments for the acquisition of the aircraft and other equipment
Aircraft to be acquired under non-binding commitment | aircraft			45