Impact of the COVID-19 Pandemic - CARES Act (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended	60 Months Ended
	Apr. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2020	Apr. 30, 2030
Impact Of Global Pandemic [Line Items]
Emergency relief per agreement through payroll support program, CARES Act	$ 5,400
Grant awarded per agreement through payroll support program, CARES Act	$ 3,800
Proceeds from payroll support program, CARES Act		$ 4,900
Proceeds from grant through payroll support program, CARES Act		3,500
CARES Act grant recognized as contra expense		1,280	$ 0	$ 1,280	$ 0
CARES Act grant deferred		2,200		2,200
Expected eligibility amount for secured loans through CARES Act		$ 4,600		$ 4,600
Delta Common Stock Warrants
Impact Of Global Pandemic [Line Items]
Number shares called by warrants (in shares)	6.5	5.9		5.9
Warrant exercise price (USD per share)	$ 24.39
Warrants term (in years)	5 years
Forecast
Impact Of Global Pandemic [Line Items]
Expected additional liquidity through deferred payment of employer portion of social security taxes						$ 200
Unsecured Debt | Unsecured CARES Act Payroll Support Program Loan
Impact Of Global Pandemic [Line Items]
Unsecured loan per agreement through payroll support program, CARES Act	$ 1,600
Debt instrument term	10 years
Interest rate per annum (percent)	1.00%	1.00%		1.00%
Proceeds from unsecured loan through payroll support program, CARES Act		$ 1,400
Unsecured Debt | Unsecured CARES Act Payroll Support Program Loan | SOFR | Forecast
Impact Of Global Pandemic [Line Items]
Basis spread on variable rate (percent)							2.00%