Condensed Statements Of Cash Flows (unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Statement of Cash Flows [Abstract]
Net cash provided by operating activities	$ 134,260	$ 97,420
Investing activities:
Proceeds from sale of slots	0	9,074
Pre-delivery deposits for flight equipment, net of refunds	(19,748)	4,738
Purchase of property and equipment	(13,816)	(19,218)
Net cash used in investing activities	(33,564)	(5,406)
Financing activities:
Proceeds from options exercised	555	303
Proceeds from sale and leaseback transactions	6,900	5,627
Payments to pre-IPO shareholders pursuant to tax receivable agreement	0	26,905
Excess tax benefits from share-based compensation	875	1,466
Repurchase of common stock	(937)	(856)
Net cash provided by (used in) financing activities	7,393	(20,365)
Net increase in cash and cash equivalents	108,089	71,649
Cash and cash equivalents at beginning of period	416,816	343,328
Cash and cash equivalents at end of period	524,905	414,977
Cash payments for:
Interest	17	287
Taxes	$ 44,806	$ 21,819