Investment in Other Companies (Details) (USD $)	12 Months Ended			0 Months Ended	1 Months Ended	12 Months Ended	0 Months Ended			1 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 TRIP	Jul. 12, 2012 TRIP Sale of interest item	Sep. 30, 2008 TRIP Common stock	Dec. 31, 2013 Trip Investimentos Ltda. item	Jul. 12, 2012 Trip Investimentos Ltda. Sale of interest Minimum	Jul. 12, 2012 Trip Investimentos Ltda. Sale of interest Maximum	Sep. 29, 2010 Air Mekong	Sep. 30, 2010 Air Mekong	Dec. 31, 2013 Air Mekong	Dec. 31, 2011 Air Mekong
Investment in other companies
Percentage ownership acquired					20.00%					30.00%
Company's investment balance			$ 19,100,000
Annual rate of return used to calculate the put option price (as a percent)			5.00%
Proceeds from sale of equity method investment	16,658,000	8,064,000		42,000,000		26,200,000
Number of installments				3		3
Period of payment under the purchase agreement				2 years
Option to acquire ownership (as a percent)				15.38%		15.38%
Option exercise period							2 years	4 years
Number of installment payments received						2
Third installment of equity interest sold						16,800,000
Payments to acquire equity method investment									7,000,000			3,000,000
Gain on sale of cost method investment											5,000,000
Other income recognized on termination of sub-lease with Air Mekong											$ 5,100,000