Loss Per Share - Summary of Warrants Outstanding (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021
Class of Warrant or Right [Line Items]
Number of shares of common stock (in shares)	10.0
PSP1 Note | Unsecured Debt
Class of Warrant or Right [Line Items]
Face amount	$ 1,500
Term of debt	10 years
PSP1 Warrants
Class of Warrant or Right [Line Items]
Number of shares of common stock (in shares)	4.8
Exercise price (in dollars per share)	$ 31.50
CARES Act Loan Warrants
Class of Warrant or Right [Line Items]
Number of shares of common stock (in shares)	1.7
Exercise price (in dollars per share)	$ 31.50
PSP2 Warrants
Class of Warrant or Right [Line Items]
Number of shares of common stock (in shares)	2.0
Exercise price (in dollars per share)	$ 43.26	$ 43.26
PSP3 Warrants
Class of Warrant or Right [Line Items]
Number of shares of common stock (in shares)	1.5
Exercise price (in dollars per share)	$ 53.92