CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
NET CASH PROVIDED BY OPERATING ACTIVITIES	$ 32,489	$ 129,277
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(112,664)	(294,649)
Sales of marketable securities	215,005	344,682
Proceeds from the sale of equipment	3	102
Acquisition of property and equipment:
Aircraft and rotable spare parts	(297,758)	(44,469)
Deposits on aircraft		(24,200)
Buildings and ground equipment	(11,644)	(4,442)
Increase in other assets	(13,563)	(11,719)
NET CASH USED IN INVESTING ACTIVITIES	(220,621)	(34,695)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of long-term debt	187,389
Principal payments on long-term debt	(88,236)	(85,971)
Tax benefit (deficiency) from exercise of common stock options	(1,266)	(175)
Net proceeds from issuance of common stock	1,933	2,666
Purchase of treasury stock	(8,414)	(196)
Payment of cash dividends	(4,119)	(4,132)
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	87,287	(87,808)
Increase (decrease) in cash and cash equivalents	(100,845)	6,774
Cash and cash equivalents at beginning of period	170,636	133,772
CASH AND CASH EQUIVALENTS AT END OF PERIOD	69,791	140,546
Cash paid during the year for:
Interest, net of capitalized amounts	33,103	36,633
Income taxes	$ 382	$ 880