Boeing 737 MAX Aircraft Grounding (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) aircraft	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) aircraft	Sep. 30, 2019 USD ($)
Number of Aircraft Grounded Under Emergency Order	34		34
After-Tax Potential Concessions and Other Considerations Announced July 2019 | $	$ 4,900		$ 4,900
Pre-Tax Potential Concessions and Other Considerations Announced January 2020 | $	$ 2,600		$ 2,600
Number of Aircraft Not Delivered Due to Grounding Under Emergency Order	41		41
Supplier Proceeds | $	$ 0	$ 0	$ (428)	$ 0
Contract to Own Aircraft
Number of Aircraft Not Delivered Due to Grounding Under Emergency Order	28		28
Contract to Lease Aircraft
Number of Aircraft Not Delivered Due to Grounding Under Emergency Order	13		13
B-737-Max
Owned Assets, Number of Units	31		31