Leases and Capacity Purchase Agreements - Future Minimum Lease Payments under Operating and Capital Leases (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	[1]
Capital Leases
2019	$ 308
2020	170
2021	147
2022	123
2023	104
After 2023	1,268
Minimum lease payments	2,120
Imputed interest	(837)
Present value of minimum lease payments	1,283
Current portion	(149)	$ (128)
Long-term obligations under capital leases	1,134	$ 996
Airport Construction Projects
Operating Leases
Operating property and equipment under capital leases	886
Obligations under capital leases	920
Facility and Other Operating Leases
Operating Leases
2019	1,330
2020	1,351
2021	1,107
2022	970
2023	953
After 2023	7,029
Minimum lease payments	12,740
Aircraft Operating Leases
Operating Leases
2019	845
2020	682
2021	583
2022	407
2023	379
After 2023	1,160
Minimum lease payments	$ 4,056

[1] Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606). See Note 1 to the financial statements contained in Part II, Item 8 of this report for additional information.