CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
CURRENT ASSETS:
Cash and cash equivalents	$ 143,075	$ 133,772
Marketable securities	468,864	556,117
Restricted cash	19,555	19,553
Receivables, net	135,833	130,102
Inventories, net	119,228	113,581
Prepaid aircraft rents	381,473	325,999
Deferred tax assets	121,986	124,320
Other current assets	23,110	30,596
Total current assets	1,413,124	1,434,040
PROPERTY AND EQUIPMENT:
Aircraft and rotable spares	4,014,946	3,997,926
Buildings and ground equipment	272,776	274,085
Total property and equipment, gross	4,287,722	4,272,011
Less-accumulated depreciation and amortization	(1,608,537)	(1,561,015)
Total property and equipment, net	2,679,185	2,710,996
OTHER ASSETS
Intangible assets, net	16,685	17,248
Other assets	111,392	92,353
Total other assets	128,077	109,601
Total assets	4,220,386	4,254,637
CURRENT LIABILITIES:
Current maturities of long-term debt	172,759	171,454
Accounts payable	227,127	222,671
Accrued salaries, wages and benefits	117,860	121,352
Accrued aircraft rents	11,862	12,745
Taxes other than income taxes	16,417	22,353
Income tax payable	538	1,255
Other current liabilities	40,572	39,595
Total current liabilities	587,135	591,425
OTHER LONG-TERM LIABILITIES	57,628	57,422
LONG-TERM DEBT, net of current maturities	1,437,635	1,470,568
DEFERRED INCOME TAXES PAYABLE	657,760	657,620
DEFERRED AIRCRAFT CREDITS	88,069	90,427
COMMITMENTS AND CONTINGENCIES
STOCKHOLDERS' EQUITY:
Preferred stock, 5,000,000 shares authorized; none issued
Common stock, no par value, 120,000,000 shares authorized; 77,172,934 and 76,713,154 shares issued, respectively	613,720	609,763
Retained earnings	1,148,277	1,147,117
Treasury stock, at cost, 25,295,636 and 25,280,364 shares, respectively	(371,407)	(371,211)
Accumulated other comprehensive income	1,569	1,506
Total stockholders' equity	1,392,159	1,387,175
Total liabilities and stockholders' equity	$ 4,220,386	$ 4,254,637