CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
CURRENT ASSETS:
Cash and cash equivalents	$ 133,772	$ 129,526
Marketable securities	556,117	497,552
Restricted cash	19,553	19,434
Income tax receivable		1,568
Receivables, net	130,102	130,510
Inventories, net	113,581	115,211
Prepaid aircraft rents	325,999	285,737
Deferred tax assets	124,320	69,519
Other current assets	30,596	31,407
Total current assets	1,434,040	1,280,464
PROPERTY AND EQUIPMENT:
Aircraft and rotable spares	3,997,926	3,973,027
Buildings and ground equipment	274,085	291,294
Total property and equipment, gross	4,272,011	4,264,321
Less-accumulated depreciation and amortization	(1,561,015)	(1,380,846)
Total property and equipment, net	2,710,996	2,883,475
OTHER ASSETS
Intangible assets, net	17,248	19,497
Other assets	92,353	98,472
Total other assets	109,601	117,969
Total assets	4,254,637	4,281,908
CURRENT LIABILITIES:
Current maturities of long-term debt	171,454	208,398
Accounts payable	222,671	220,784
Accrued salaries, wages and benefits	121,352	112,987
Accrued aircraft rents	12,745	22,285
Taxes other than income taxes	22,353	21,186
Income tax payable	1,255
Other current liabilities	39,595	38,508
Total current liabilities	591,425	624,148
OTHER LONG TERM LIABILITIES	57,422	50,194
LONG TERM DEBT, net of current maturities	1,470,568	1,606,993
DEFERRED INCOME TAXES PAYABLE	657,620	567,874
DEFERRED AIRCRAFT CREDITS	90,427	98,438
COMMITMENTS AND CONTINGENCIES (Note 6)
STOCKHOLDERS' EQUITY:
Preferred stock, 5,000,000 shares authorized; none issued
Common stock, no par value, 120,000,000 shares authorized; 76,713,154 and 75,833,696 shares issued, respectively	609,763	598,985
Retained earnings	1,147,117	1,104,144
Treasury stock, at cost, 25,280,364 and 25,221,481 shares, respectively	(371,211)	(370,309)
Accumulated other comprehensive income (Note 1)	1,506	1,441
Total stockholders' equity	1,387,175	1,334,261
Total liabilities and stockholders' equity	$ 4,254,637	$ 4,281,908