Condensed Statements Of Cash Flows (unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Statement of Cash Flows [Abstract]
Net cash provided by operating activities	$ 173,631	$ 88,807
Investing activities:
Proceeds from sale of property and equipment	0	14
Proceeds from sale of slots	0	9,060
Pre-delivery deposits for flight equipment, net of refunds	(41,328)	(6,817)
Purchase of property and equipment	(17,028)	(21,711)
Net cash used in investing activities	(58,356)	(19,454)
Financing activities:
Proceeds from options exercised	675	410
Proceeds from sale and leaseback transactions	6,900	12,427
Payments to pre-IPO shareholders pursuant to tax receivable agreement	0	(26,905)
Excess tax benefits from share-based compensation	1,635	1,466
Repurchase of common stock	(1,106)	(936)
Net cash provided by (used in) financing activities	8,104	(13,538)
Net increase in cash and cash equivalents	123,379	55,815
Cash and cash equivalents at beginning of period	416,816	343,328
Cash and cash equivalents at end of period	540,195	399,143
Cash payments for:
Interest	26	297
Taxes	$ 60,942	$ 39,350