CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
CURRENT ASSETS:
Cash and cash equivalents	$ 181,792	$ 146,766
Marketable securities	503,503	409,898
Restricted cash		8,243
Income tax receivable	5,316	6,989
Receivables, net	42,731	46,916
Inventories, net	119,755	118,509
Prepaid aircraft rents	115,098	162,360
Other current assets	26,938	18,111
Total current assets	995,133	917,792
PROPERTY AND EQUIPMENT:
Aircraft and rotable spares	5,335,870	4,839,501
Deposits on aircraft	49,000	38,800
Buildings and ground equipment	265,608	261,704
Total property and equipment, gross	5,650,478	5,140,005
Less-accumulated depreciation and amortization	(1,467,475)	(1,318,308)
Total property and equipment, net	4,183,003	3,821,697
OTHER ASSETS
Long-term prepaid assets	230,923	218,505
Other long-term assets	49,220	49,972
Total other assets	280,143	268,477
Total assets	5,458,279	5,007,966
CURRENT LIABILITIES:
Current maturities of long-term debt	309,678	305,460
Accounts payable	288,904	241,215
Accrued salaries, wages and benefits	154,367	139,885
Taxes other than income taxes	19,228	15,618
Other current liabilities	48,648	45,087
Total current liabilities	820,825	747,265
OTHER LONG TERM LIABILITIES	42,541	50,844
LONG TERM DEBT, net of current maturities	2,377,346	2,240,051
DEFERRED INCOME TAXES PAYABLE	419,020	565,404
DEFERRED AIRCRAFT CREDITS	44,225	53,459
COMMITMENTS AND CONTINGENCIES (Note 5)
STOCKHOLDERS' EQUITY:
Preferred stock, 5,000,000 shares authorized; none issued
Common stock, no par value, 120,000,000 shares authorized; 80,398,104 and 79,781,305 shares issued, respectively	672,593	657,353
Retained earnings	1,516,957	1,103,751
Treasury stock, at cost, 28,643,535 and 28,015,386 shares, respectively	(435,178)	(410,090)
Accumulated other comprehensive loss	(50)	(71)
Total stockholders' equity	1,754,322	1,350,943
Total liabilities and stockholders' equity	$ 5,458,279	$ 5,007,966