CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 289,544	$ 87,206
Marketable securities	288,351	432,966
Income tax receivable	18,945	11,141
Receivables, net	37,197	82,977
Inventories, net	104,800	110,503
Other current assets	30,131	35,553
Total current assets	768,968	760,346
PROPERTY AND EQUIPMENT:
Aircraft and rotable spares	7,203,714	7,078,801
Deposits on aircraft	48,858	48,858
Buildings and ground equipment	244,751	265,398
Total property and equipment, gross	7,497,323	7,393,057
Less-accumulated depreciation and amortization	(2,103,585)	(1,998,376)
Total property and equipment, net	5,393,738	5,394,681
OTHER ASSETS:
Operating lease right-of-use assets	326,698	336,009
Other assets	172,007	166,093
Total other assets	498,705	502,102
Total assets	6,661,411	6,657,129
CURRENT LIABILITIES:
Current maturities of long-term debt	364,579	364,126
Accounts payable	407,290	284,473
Accrued salaries, wages and benefits	112,972	133,856
Current maturities of operating lease liabilities	88,649	94,806
Taxes other than income taxes	14,148	15,004
Other current liabilities	32,205	32,411
Total current liabilities	1,019,843	924,676
LONG-TERM DEBT, net of current maturities	2,537,613	2,628,989
DEFERRED INCOME TAXES PAYABLE	633,110	623,580
NONCURRENT OPERATING LEASE LIABILITIES	259,039	259,237
OTHER LONG-TERM LIABILITIES	48,368	45,633
COMMITMENTS AND CONTINGENCIES (Note 7)
STOCKHOLDERS' EQUITY:
Preferred stock, 5,000,000 shares authorized; none issued
Common stock, no par value, 120,000,000 shares authorized; 82,053,807 and 81,742,937 shares issued, respectively	690,065	686,806
Retained earnings	2,090,509	2,079,179
Treasury stock, at cost, 31,913,635 and 31,420,179 shares, respectively	(617,136)	(590,971)
Total stockholders' equity	2,163,438	2,175,014
Total liabilities and stockholders' equity	$ 6,661,411	$ 6,657,129