Passenger Ticket Revenues Attributed to Geographic Areas Based on Where Reservation Originates (Detail)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
United States
Passengers ticket revenue, percentage
Passengers ticket revenue, percentage	51.00%	55.00%	54.00%
All other countries
Passengers ticket revenue, percentage
Passengers ticket revenue, percentage	49.00%	45.00%	46.00%