CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
NET CASH PROVIDED BY OPERATING ACTIVITIES	$ 51,324	$ 133,428
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of marketable securities	(234,342)	(390,615)
Sales of marketable securities	382,351	355,195
Payments received on note receivable from United Air Lines		4,000
Proceeds from the sale of equipment	191	114
Acquisition of property and equipment:
Aircraft and rotable spare parts	(29,029)	(111,298)
Deposits on aircraft	(13,500)
Buildings and ground equipment	(5,009)	(4,172)
Increase in other assets	(3,850)	(12,600)
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	96,812	(159,376)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of long-term debt		81,698
Principal payments on long-term debt	(79,363)	(74,045)
Tax benefit from exercise of common stock options	2
Return of deposits on aircraft and rotable spare parts	400	4,247
Net proceeds from issuance of common stock	2,203	2,504
Purchase of treasury stock	(40,259)	(1,179)
Payment of cash dividends	(4,326)	(4,511)
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	(121,343)	8,714
Increase (decrease) in cash and cash equivalents	26,793	(17,234)
Cash and cash equivalents at beginning of period	112,338	76,414
CASH AND CASH EQUIVALENTS AT END OF PERIOD	139,131	59,180
Cash paid during the year for:
Interest, net of capitalized amounts	41,370	42,698
Income taxes	$ 698	$ 495