Condensed Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities:
Net income	$ 254,041	$ 63,812
Adjustments to reconcile net income to net cash provided by operations:
Losses reclassified from other comprehensive income	220	238
Share-based compensation	8,128	8,293
Allowance for doubtful accounts (recoveries)	0	(12)
Amortization of deferred gains and losses and debt issuance costs	6,540	6,508
Depreciation and amortization	163,351	128,764
Deferred income tax expense	91,688	21,243
Loss on disposal of assets	16,873	6,561
Special charges, non-operating	0	90,357
Changes in operating assets and liabilities:
Accounts receivable, net	(23,712)	(14,191)
Aircraft maintenance deposits, net	(14,955)	10,543
Prepaid income taxes	1,431	0
Other assets	(24,474)	(5,760)
Deferred heavy maintenance, net	(123,299)	(121,643)
Income tax receivable	(21,693)	(8,662)
Accounts payable	883	38,771
Air traffic liability	69,237	59,916
Other liabilities	(45,169)	23,896
Other	(693)	(136)
Net cash provided by operating activities	358,397	308,498
Investing activities:
Purchase of available-for-sale investment securities	(93,557)	(100,228)
Proceeds from the maturity of available-for-sale investment securities	92,395	99,134
Proceeds from sale of property and equipment	0	9,500
Pre-delivery deposits on flight equipment, net of refunds	(169,200)	(132,297)
Capitalized interest	(7,707)	(6,116)
Assets under construction for others	(7,591)	0
Purchase of property and equipment	(114,396)	(420,586)
Net cash used in investing activities	(300,056)	(550,593)
Financing activities:
Proceeds from issuance of long-term debt	94,706	518,171
Proceeds from stock options exercised	1	5
Payments on debt obligations	(125,914)	(93,225)
Payments on finance lease obligations	(95,608)	(205,566)
Reimbursement for assets under construction for others	5,389	0
Repurchase of common stock	(5,356)	(1,145)
Debt issuance costs	(614)	(3,284)
Net cash (used in) provided by financing activities	(127,396)	214,956
Net decrease in cash and cash equivalents	(69,055)	(27,139)
Cash and cash equivalents at beginning of period	1,004,733	800,849
Cash and cash equivalents at end of period	935,678	773,710
Cash payments for:
Interest, net of capitalized interest	59,840	35,977
Income taxes paid, net of refunds	8,288	3,366
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	141,019	0
Financing cash flows for finance leases	641	0
Non-cash transactions:
Capital expenditures funded by finance lease borrowings	96,371	144,106
Capital expenditures funded by operating lease borrowings	$ 189,487	$ 0