Commitments and Contingencies - Employees (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Unionized Employees Concentration Risk [Member] Number of Employees, Total [Member]	Mar. 31, 2013 Unionized Employees Concentration Risk [Member] Number of Employees, Total [Member] Association of Flight Attendants [Member]	Mar. 31, 2013 Unionized Employees Concentration Risk [Member] Number of Employees, Total [Member] Air Line Pilots Association, International [Member]	Mar. 31, 2013 Unionized Employees Concentration Risk [Member] Number of Employees, Total [Member] Transport Workers Union [Member]
Multiemployer Plans [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)			56.00%	33.00%	22.00%	1.00%
Accrued health care claims	$ 1.9	$ 1.9