CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
CURRENT ASSETS:
Cash and cash equivalents	$ 82,603	$ 170,636
Marketable securities	447,908	487,239
Restricted cash	12,219	12,219
Income tax receivable	6,366	840
Receivables, net	121,130	111,186
Inventories, net	143,346	138,094
Prepaid aircraft rents	416,847	360,781
Deferred tax assets	160,639	156,050
Other current assets	18,707	27,392
Total current assets	1,409,765	1,464,437
PROPERTY AND EQUIPMENT:
Aircraft and rotable spares	4,121,304	4,080,886
Deposits on aircraft	40,000	40,000
Buildings and ground equipment	301,870	279,965
Total property and equipment, gross	4,463,174	4,400,851
Less-accumulated depreciation and amortization	(1,797,987)	(1,749,058)
Total property and equipment, net	2,665,187	2,651,793
OTHER ASSETS
Intangible assets, net	14,436	14,998
Other assets	112,639	101,991
Total other assets	127,075	116,989
Total assets	4,202,027	4,233,219
CURRENT LIABILITIES:
Current maturities of long-term debt	181,379	177,389
Accounts payable	269,306	245,518
Accrued salaries, wages and benefits	124,812	133,002
Accrued aircraft rents	3,082	7,492
Taxes other than income taxes	13,825	19,626
Other current liabilities	43,788	37,437
Total current liabilities	636,192	620,464
OTHER LONG-TERM LIABILITIES	73,475	76,305
LONG-TERM DEBT, net of current maturities	1,285,538	1,293,179
DEFERRED INCOME TAXES PAYABLE	718,048	727,358
DEFERRED AIRCRAFT CREDITS	79,550	80,974
COMMITMENTS AND CONTINGENCIES
STOCKHOLDERS' EQUITY:
Preferred stock, 5,000,000 shares authorized; none issued
Common stock, no par value, 120,000,000 shares authorized; 77,709,080 and 77,325,702 shares issued, respectively	620,800	618,511
Retained earnings	1,172,867	1,197,819
Treasury stock, at cost, 26,337,886 and 26,095,636 shares, respectively	(386,026)	(382,950)
Accumulated other comprehensive income	1,583	1,559
Total stockholders' equity	1,409,224	1,434,939
Total liabilities and stockholders' equity	$ 4,202,027	$ 4,233,219