CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
NET CASH PROVIDED BY OPERATING ACTIVITIES	$ 492,283	$ 362,123
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(475,156)	(896,326)
Sales of marketable securities	598,606	961,403
Proceeds from the sale of aircraft, property and equipment	1,366	21,065
Acquisition of property and equipment:
Aircraft and rotable spare parts	(161,167)	(325,969)
Buildings and ground equipment	(8,695)	(55,865)
Deposits on aircraft	(625)	(31,817)
Aircraft deposits applied towards acquired aircraft	9,220	23,298
Net cash received from sale of ExpressJet subsidiary		53,200
Decrease (increase) in other assets	(34,172)	1,962
NET CASH USED IN INVESTING ACTIVITIES	(70,623)	(249,049)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of long-term debt	98,059	99,914
Principal payments on long-term debt	(115,189)	(211,200)
Net proceeds from issuance of common stock	1,532	4,540
Purchase of treasury and common stock and employee income tax paid on equity awards	(26,165)	(68,932)
Increase in debt issuance and lessor initial direct costs	(1,797)	(820)
Payment of cash dividends	(13,059)	(11,299)
NET CASH PROVIDED USED IN FINANCING ACTIVITIES	(56,619)	(187,797)
Increase (decrease) in cash and cash equivalents	365,041	(74,723)
Cash and cash equivalents at beginning of period	87,206	328,384
CASH AND CASH EQUIVALENTS AT END OF PERIOD	452,247	253,661
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Acquisition of rotable spare parts	13,522	3,244
Debt assumed on aircraft acquired under operating leases		14,475
Engines contributed to joint venture		22,313
Non-cash assets used to acquire aircraft under operating leases		150,688
Lease liability arising from the recognition of right-of-use asset		456,472
CARES Act warrant issuance	2,845
Cash paid during the period for:
Interest, net of capitalized amounts	41,881	67,778
Income taxes	$ 303	1,713
SUPPLEMENTAL DISCLOSURE OF SALE OF SUBSIDIARY:
Decrease in carrying amount of assets		(101,448)
Decrease in carrying amount of liabilities		68,341
Cash received from buyers		79,632
Gain on sale of subsidiary		$ 46,525