Commitments and Contingencies - Employees (Details) - Unionized Employees Concentration Risk - Number of Employees, Total	6 Months Ended
	Jun. 30, 2021 employee_group
Concentration Risk [Line Items]
Number of union-represented employee groups	5
Company's employees covered under collective bargaining agreements (as a percent)	81.00%
Air Line Pilots Association, International ("ALPA")
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)	28.00%
Association of Flight Attendants ("AFA-CWA")
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)	46.00%
Professional Airline Flight Control Association ("PAFCA")
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)	1.00%
International Association of Machinists and Aerospace Workers ("IAMAW")
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)	3.00%
Transport Workers Union of America ("TWU")
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)	3.00%