Commitments and Contingencies - Employees (Details) $ in Millions	1 Months Ended		9 Months Ended
	May. 31, 2015	Aug. 31, 2014	Sep. 30, 2015 USD ($) airport	Dec. 31, 2014 USD ($)
Concentration Risk [Line Items]
Number of airports in which entity operates			56
Association of Flight Attendants [Member]
Concentration Risk [Line Items]
Tentative collective bargaining agreement, contract term		5 years
International Association Of Machinists And Aerospace Workers (IAM) [Member]
Concentration Risk [Line Items]
Interim collective bargaining agreement, contract term	5 years
Number of airports in which entity operates			1
Health Insurance [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Accrued health care claims | $			$ 3.6	$ 3.1
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member]
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)			73.00%
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member] | Air Line Pilots Association, International [Member]
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)			26.00%
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member] | Association of Flight Attendants [Member]
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)			43.00%
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member] | Transport Workers Union [Member]
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)			1.00%
Unionized Employees Concentration Risk [Member] | Number of Employees, Total [Member] | International Association Of Machinists And Aerospace Workers (IAM) [Member]
Concentration Risk [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)			3.00%