CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
CURRENT ASSETS:
Cash and cash equivalents	$ 246,001	$ 258,421
Marketable securities	610,450	601,989
Receivables, net	68,039	65,348
Inventories, net	110,041	104,093
Other current assets	37,438	38,742
Total current assets	1,071,969	1,068,593
PROPERTY AND EQUIPMENT:
Aircraft and rotable spares	7,960,911	7,848,100
Deposits on aircraft	129,514	124,964
Buildings and ground equipment	263,999	256,595
Total property and equipment, gross	8,354,424	8,229,659
Less-accumulated depreciation and amortization	(2,825,603)	(2,731,060)
Total property and equipment, net	5,528,821	5,498,599
OTHER ASSETS:
Operating lease right-of-use assets	223,856	238,516
Long-term receivables and other assets	324,312	320,239
Total other assets	548,168	558,755
Total assets	7,148,958	7,125,947
CURRENT LIABILITIES:
Current maturities of long-term debt	410,124	391,798
Accounts payable	412,757	496,333
Accrued salaries, wages and benefits	157,211	150,583
Current maturities of operating lease liabilities	78,930	78,886
Taxes other than income taxes	26,669	28,869
Other current liabilities	56,597	48,152
Total current liabilities	1,142,288	1,194,621
LONG-TERM DEBT, net of current maturities	2,791,274	2,717,420
DEFERRED INCOME TAXES PAYABLE	669,026	663,236
NONCURRENT OPERATING LEASE LIABILITIES	147,994	158,274
OTHER LONG-TERM LIABILITIES	108,661	124,882
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; 82,514,936 and 82,335,970 shares issued as of March 31, 2022, and December 31, 2021, respectively	727,900	722,310
Retained earnings	2,181,650	2,163,916
Treasury stock, at cost, 31,993,144 and 31,956,047 shares as of March 31, 2022, and December 31, 2021, respectively	(619,835)	(618,712)
Total stockholders' equity	2,289,715	2,267,514
Total liabilities and stockholders' equity	$ 7,148,958	$ 7,125,947