Commitments and Contingencies - Employees (Details) (USD $) In Millions, unless otherwise specified			9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Unionized Employees Concentration Risk [Member] Workforce Subject to Collective Bargaining Arrangements [Member]	Sep. 30, 2012 Unionized Employees Concentration Risk [Member] Workforce Subject to Collective Bargaining Arrangements [Member] Air Line Pilots Association, International [Member]	Sep. 30, 2012 Unionized Employees Concentration Risk [Member] Workforce Subject to Collective Bargaining Arrangements [Member] Association of Flight Attendants [Member]	Sep. 30, 2012 Unionized Employees Concentration Risk [Member] Workforce Subject to Collective Bargaining Arrangements [Member] Transport Workers Union [Member]
Multiemployer Plans [Line Items]
Company's employees covered under collective bargaining agreements (as a percent)			52.00%	22.00%	29.00%	1.00%
Accrued health care claims	$ 1.5	$ 2.0