Commitments - Schedule of Purchase Commitments (Details) $ in Millions	Feb. 28, 2019 USD ($)
Unrecorded Unconditional Purchase Obligation [Line Items]
2019 (remainder)	$ 717
2020	2,831
2021	2,873
2022	2,307
2023	1,861
Thereafter	3,614
Total	14,203
Aircraft And Related Equipment Commitments [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2019 (remainder)	421
2020	1,998
2021	2,276
2022	1,874
2023	1,586
Thereafter	3,079
Total	11,234
Other Commitments [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2019 (remainder)	296	[1]
2020	833	[1]
2021	597	[1]
2022	433	[1]
2023	275	[1]
Thereafter	535	[1]
Total	$ 2,969	[1]

[1] Primarily equipment and advertising contracts.