Condensed Statements of Cash Flows (unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating activities:
Net income (loss)	$ (27,828,000)	$ 56,076,000
Adjustments to reconcile net income (loss) to net cash provided by operations:
Losses reclassified from other comprehensive income	65,000	74,000
Share-based compensation	3,790,000	3,671,000
Amortization of deferred gains, losses and debt issuance costs	2,106,000	2,289,000
Depreciation and amortization	65,991,000	50,726,000
Deferred income tax expense	36,367,000	11,647,000
Loss on disposal of assets	0	1,913,000
Changes in operating assets and liabilities:
Accounts receivable, net	39,910,000	(23,285,000)
Aircraft maintenance deposits, net	(1,330,000)	(2,559,000)
Long-term deposits and other assets	(666,000)	20,735,000
Deferred heavy maintenance, net	(35,564,000)	(44,161,000)
Income tax receivable	(83,213,000)	0
Accounts payable	14,854,000	(13,543,000)
Air traffic liability	95,876,000	111,020,000
Other liabilities	(75,541,000)	30,712,000
Other	(235,000)	(164,000)
Net cash provided by operating activities	34,582,000	205,151,000
Investing activities:
Purchase of available-for-sale investment securities	(24,036,000)	(26,476,000)
Proceeds from the maturity and sale of available-for-sale investment securities	23,600,000	26,085,000
Pre-delivery deposits on flight equipment, net of refunds	(123,044,000)	(37,913,000)
Capitalized interest	(2,860,000)	(2,276,000)
Assets under construction for others	(2,057,000)	(262,000)
Purchase of property and equipment	(195,371,000)	(63,109,000)
Net cash used in investing activities	(323,768,000)	(103,951,000)
Financing activities:
Proceeds from issuance of long-term debt	168,981,000	59,706,000
Proceeds from stock options exercised	16,000	0
Payments on debt obligations	(42,561,000)	(37,901,000)
Payments on finance lease obligations	(24,846,000)	(239,000)
Reimbursement for assets under construction for others	2,095,000	262,000
Repurchase of common stock	(1,536,000)	(5,223,000)
Debt issuance costs	(3,695,000)	(399,000)
Net cash provided by financing activities	98,454,000	16,206,000
Net increase (decrease) in cash and cash equivalents	(190,732,000)	117,406,000
Cash and cash equivalents at beginning of period	978,957,000	1,004,733,000
Cash and cash equivalents at end of period	788,225,000	1,122,139,000
Cash payments for:
Interest, net of capitalized interest	17,702,000	19,167,000
Income taxes paid (received), net	(1,497,000)	816,000
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	50,805,000	47,577,000
Financing cash flows for finance leases	113,000	29,000
Non-cash transactions:
Capital expenditures funded by finance lease borrowings	0	1,492,000
Capital expenditures funded by operating lease borrowings	$ 85,787,000	$ 128,191,000