Condensed Statements Of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating activities:
Net income	$ 31,935	$ 61,920
Adjustments to reconcile net income to net cash provided by operations:
Losses reclassified from other comprehensive income	84	90
Equity-based compensation	2,816	1,790
Allowance for doubtful accounts (recoveries)	(30)	25
Amortization of deferred gains and losses and debt issuance costs	3,351	1,968
Depreciation and amortization	31,509	23,109
Deferred income tax expense	19,474	21,066
Loss on disposal of assets	1,105	214
Lease termination costs	4,776	16,202
Changes in operating assets and liabilities:
Accounts receivable	(7,526)	(4,229)
Aircraft maintenance deposits	(12,774)	(12,311)
Prepaid income taxes	(846)	72,278
Long-term deposits and other assets	(21,267)	(8,495)
Accounts payable	18,937	4,703
Air traffic liability	102,207	46,473
Other liabilities	298	33,296
Other	113	0
Net cash provided by operating activities	174,162	258,099
Investing activities:
Purchase of available-for-sale investment securities	(24,490)	0
Proceeds from the maturity of available-for-sale investment securities	24,219	0
Pre-delivery deposits for flight equipment, net of refunds	(44,752)	(50,358)
Capitalized interest	(1,647)	(2,575)
Purchase of property and equipment	(112,265)	(159,829)
Net cash used in investing activities	(158,935)	(212,762)
Financing activities:
Proceeds from issuance of long-term debt	115,526	73,914
Proceeds from stock options exercised	0	88
Payments on debt and capital lease obligations	(10,235)	(9,749)
Excess tax (deficiency) benefit from equity-based compensation	0	(778)
Repurchase of common stock	(1,034)	(9,601)
Debt issuance costs	(2,274)	(34)
Net cash provided by financing activities	101,983	53,840
Net (decrease) increase in cash and cash equivalents	117,210	99,177
Cash and cash equivalents at beginning of period	700,900	803,632
Cash and cash equivalents at end of period	818,110	902,809
Cash payments for:
Interest, net of capitalized interest	3,943	3,430
Income taxes paid, net of refunds	2,881	(64,158)
Non-cash transactions:
Capital expenditures funded by capital lease borrowings	$ (130)	$ (31)