Impact of the COVID-19 Pandemic - Valuation of Long-Lived Assets (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020 aircraft	Mar. 31, 2020 USD ($) aircraft	Jun. 30, 2020 aircraft
Property, Plant and Equipment [Line Items]
Flight equipment and other long-lived assets | $		$ 31,600
Number of aircraft removed from active service | aircraft		400
MD-88
Property, Plant and Equipment [Line Items]
Impairment charge related to retired fleet | $		$ 22
Forecast
Property, Plant and Equipment [Line Items]
Number of aircraft removed from active service | aircraft	250		650