CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
NET CASH PROVIDED BY OPERATING ACTIVITIES	$ 498,688	$ 492,283
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(798,877)	(475,156)
Sales of marketable securities	799,241	598,606
Acquisition of property and equipment:
Aircraft and rotable spare parts	(63,450)	(161,167)
Buildings and ground equipment	(8,700)	(8,695)
Proceeds from the sale of property and equipment	2,282	1,366
Deposits on aircraft	(58,269)	(625)
Return of deposits applied towards acquired aircraft		9,220
Increase in other assets	(54,608)	(34,172)
NET CASH USED IN INVESTING ACTIVITIES	(182,381)	(70,623)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of long-term debt	95,430	98,059
Principal payments on long-term debt	(281,778)	(115,189)
Net proceeds from issuance of common stock	1,745	1,532
Purchase of treasury stock		(20,000)
Employee income tax paid on vested equity awards	(1,573)	(6,165)
Payment of debt issuance cost		(1,797)
Payment of cash dividends		(13,059)
NET CASH USED IN FINANCING ACTIVITIES	(186,176)	(56,619)
Increase in cash and cash equivalents	130,131	365,041
Cash and cash equivalents at beginning of period	215,723	87,206
CASH AND CASH EQUIVALENTS AT END OF PERIOD	345,854	452,247
Non-cash investing and financing activities:
Acquisition of rotable spare parts	11,797	13,522
Warrants issued to U.S. Treasury	5,804	2,845
Cash paid during the period for:
Interest, net of capitalized amounts	66,767	41,881
Income taxes	$ 457	$ 303