CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
NET CASH PROVIDED BY OPERATING ACTIVITIES	$ 399,318	$ 313,540
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(2,160,567)	(864,241)
Sales of marketable securities	1,941,209	849,942
Proceeds from the sale of aircraft, property and equipment	1,848	5,771
Acquisition of property and equipment:
Aircraft and rotable spare parts	(619,805)	(647,250)
Buildings and ground equipment	(11,256)	(7,443)
Return of deposits on aircraft		5,178
Decrease (increase) in other assets	(2,156)	1,672
NET CASH USED IN INVESTING ACTIVITIES	(850,727)	(656,371)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of long-term debt	497,510	546,232
Principal payments on long-term debt	(198,394)	(184,336)
Net proceeds from issuance of common stock	10,214	4,698
Purchase of treasury stock		(18,726)
Increase in debt issuance cost	(4,520)	(4,385)
Payment of cash dividends	(6,669)	(6,183)
NET CASH PROVIDED BY FINANCING ACTIVITIES	298,141	337,300
Decrease in cash and cash equivalents	(153,268)	(5,531)
Cash and cash equivalents at beginning of period	203,035	132,275
CASH AND CASH EQUIVALENTS AT END OF PERIOD	49,767	126,744
Cash paid during the year for:
Interest, net of capitalized amounts	54,314	56,117
Income taxes	$ 944	$ 1,494