Commitments and Contingencies - Employees (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) employee_group	Dec. 31, 2019 USD ($)
Health Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Accrued health care claims | $	$ 5.0	$ 5.2
Unionized Employees Concentration Risk | Number of Employees, Total
Concentration Risk [Line Items]
Number of union-represented employee groups | employee_group	5
Company's employees covered under collective bargaining agreements (as a percent)	81.00%
Unionized Employees Concentration Risk | Number of Employees, Total | Air Line Pilots Association, International ("ALPA")
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)	27.00%
Unionized Employees Concentration Risk | Number of Employees, Total | Association of Flight Attendants ("AFA-CWA")
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)	47.00%
Unionized Employees Concentration Risk | Number of Employees, Total | Professional Airline Flight Control Association ("PAFCA")
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)	1.00%
Unionized Employees Concentration Risk | Number of Employees, Total | 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%
Unionized Employees Concentration Risk | Number of Employees, Total | Transport Workers Union of America ("TWU")
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)	3.00%