Investments - Fair Value Investments (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jan. 31, 2020	Dec. 31, 2019
Fair Value Investments
Carrying value	$ 1,310		$ 1,099
Hanjin-KAL
Fair Value Investments
Ownership interest (percent)	15.00%		10.00%
Carrying value	$ 517		$ 205
Air France-KLM
Fair Value Investments
Ownership interest (percent)	9.00%		9.00%
Carrying value	$ 130		$ 418
China Eastern
Fair Value Investments
Ownership interest (percent)	3.00%		3.00%
Carrying value	$ 199		$ 258
Wheels Up
Fair Value Investments
Ownership interest (percent)	25.00%	27.00%	0.00%
Carrying value	$ 234		$ 0
Other investments
Fair Value Investments
Carrying value	$ 230		$ 218