Commitments and Contingencies - Credit Card Processing Arrangements (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Commitments and Contingencies Disclosure [Abstract]
Cash collateral required for credit card transactions as a percentage of air traffic liability, prior to amendment	100.00%
Cash holdback for credit card transactions	$ 0	$ 0
Maximum potential exposure to cash holdbacks from credit card processors	$ 197,000,000	$ 144,800,000