Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating activities:
Net income	$ 108,460	$ 76,448	$ 72,481
Adjustments to reconcile net income to net cash provided by operations:
Changes in fair value of open fuel hedge contracts	46	3,204	(2,065)
Non-cash restructuring credit charges, net	0	0	22
Equity based stock compensation, net	4,327	530	569
Allowance for doubtful accounts (recoveries)	78	27	(110)
Amortization of deferred gains, losses and debt issuance costs	(830)	(1,047)	(574)
Depreciation and amortization	15,256	7,760	5,620
Deferred income tax benefit (loss)	29,255	44,180	(52,811)
Loss on disposal of assets	956	255	77
Gain on slot sale	(9,060)	0	0
Interest and dividends incurred but not paid	0	21,875	43,202
Capitalized interest	(1,350)	(2,890)	(1,491)
Changes in operating assets and liabilities:
Restricted cash	0	72,736	(20,196)
Accounts receivable	(7,393)	(5,728)	(1,014)
Prepaid maintenance reserves	(31,567)	(36,848)	(35,694)
Long-term deposits and other assets	(68,248)	(15,992)	(13,981)
Accounts payable	8,452	2,457	(2,007)
Air traffic liability	19,134	6,573	19,107
Other liabilities	46,115	(2,189)	16,132
Other	0	(153)	(234)
Net cash provided by operating activities	113,631	171,198	27,033
Investing activities:
Proceeds from sale of property and equipment	14	150	333
Proceeds from sale of slots	9,060	0	0
Pre-delivery deposits for flight equipment, net of refunds	(12,626)	(53,274)	(25,474)
Purchase of property and equipment	(23,771)	(14,093)	(5,325)
Net cash used in investing activities	(27,323)	(67,217)	(30,466)
Financing activities:
Proceeds from issuance of common stock, net offering expenses	0	170,828	0
Proceeds from options exercised	469	423	0
Payments on debt and capital lease obligations	0	(18,221)	0
Proceeds from sale leaseback transactions	12,540	4,481	0
Payments to pre-IPO shareholders pursuant to tax receivable agreement	(26,905)	0	0
Excess tax benefits from share-based compensation	2,098	0	0
Repurchase of common stock	(1,022)	(886)	0
Debt issuance costs	0	8	0
Net cash (used in) provided by financing activities	(12,820)	156,633	0
Net increase (decrease) in cash and cash equivalents	73,488	260,614	(3,433)
Cash and cash equivalents at beginning of period	343,328	82,714	86,147
Cash and cash equivalents at end of period	416,816	343,328	82,714
Supplemental disclosures
Interest	303	10,562	4,303
Taxes	40,204	1,477	562
Non-cash transactions:
Exchange of notes due to related parties for common stock	0	279,206	0
Exchange of mandatorily redeemable preferred stock for common stock	0	81,747	0
Liability and equity related to tax receivable agreement	$ (1,497)	$ 36,488	$ 0