CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 258,421	$ 215,723
Marketable securities	601,989	610,185
Receivables, net	65,348	34,462
Inventories, net	104,093	91,196
Other current assets	38,742	31,236
Total current assets	1,068,593	982,802
PROPERTY AND EQUIPMENT:
Aircraft and rotable spares	7,848,100	7,527,555
Deposits on aircraft	124,964	31,625
Buildings and ground equipment	256,595	258,863
Total property and equipment, gross	8,229,659	7,818,043
Less-accumulated depreciation and amortization	(2,731,060)	(2,455,995)
Total property and equipment, net	5,498,599	5,362,048
OTHER ASSETS:
Operating lease right-of-use assets	238,516	282,362
Long-term receivables and other assets	320,239	260,410
Total other assets	558,755	542,772
Total assets	7,125,947	6,887,622
CURRENT LIABILITIES:
Current maturities of long-term debt	391,798	402,158
Accounts payable	496,333	278,677
Accrued salaries, wages and benefits	150,583	125,944
Current maturities of operating lease liabilities	78,886	82,641
Taxes other than income taxes	28,869	26,183
Other current liabilities	48,152	26,119
Total current liabilities	1,194,621	941,722
LONG-TERM DEBT, net of current maturities	2,717,420	2,801,538
DEFERRED INCOME TAXES PAYABLE	663,236	625,931
NONCURRENT OPERATING LEASE LIABILITIES	158,274	205,845
OTHER LONG-TERM LIABILITIES	124,882	173,041
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; 82,335,970 and 82,094,985 shares issued as of December 31, 2021, and December 31, 2020, respectively	722,310	704,675
Retained earnings	2,163,916	2,052,006
Treasury stock, at cost, 31,956,047 and 31,913,635 shares as of December 31, 2021, and December 31, 2020, respectively	(618,712)	(617,136)
Total stockholders' equity	2,267,514	2,139,545
Total liabilities and stockholders' equity	$ 7,125,947	$ 6,887,622