Commitments and Contingencies - Employees (Details) $ in Millions		1 Months Ended			3 Months Ended	6 Months Ended
	Mar. 31, 2016	Jun. 30, 2016 USD ($) airport	May 31, 2016	May 31, 2015	Jun. 30, 2016 USD ($) airport	Jun. 30, 2016 USD ($) airport	Dec. 31, 2015 USD ($)
Concentration Risk [Line Items]
Number of airports in which entity operates | airport		56			56	56
Association of Flight Attendants [Member]
Concentration Risk [Line Items]
Tentative collective bargaining agreement, contract term	5 years
Compensation | $		$ 9.6			$ 9.6	$ 9.6
Ratified Collective Bargaining Agreement, Contract Term			5 years
International Association Of Machinists And Aerospace Workers (IAM) [Member]
Concentration Risk [Line Items]
Tentative collective bargaining agreement, contract term				5 years
Ratified Collective Bargaining Agreement, Contract Term		5 years
Number of airports in which entity operates | airport		1			1	1
Health Insurance [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Accrued health care claims | $		$ 5.0			$ 5.0	$ 5.0	$ 4.3
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)						74.00%
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)					4.00%