CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 452,247	$ 87,206
Marketable securities	309,823	432,966
Income tax receivable	18,915	11,141
Receivables, net	42,498	82,977
Inventories, net	97,782	110,503
Other current assets	24,584	35,553
Total current assets	945,849	760,346
PROPERTY AND EQUIPMENT:
Aircraft and rotable spares	7,273,577	7,078,801
Deposits on aircraft	40,263	48,858
Buildings and ground equipment	246,131	265,398
Total property and equipment, gross	7,559,971	7,393,057
Less-accumulated depreciation and amortization	(2,233,275)	(1,998,376)
Total property and equipment, net	5,326,696	5,394,681
OTHER ASSETS:
Operating lease right-of-use assets	310,016	336,009
Other assets	190,822	166,093
Total other assets	500,838	502,102
Total assets	6,773,383	6,657,129
CURRENT LIABILITIES:
Current maturities of long-term debt	309,159	364,126
Accounts payable	322,460	284,473
Accrued salaries, wages and benefits	108,929	133,856
Current maturities of operating lease liabilities	87,415	94,806
Taxes other than income taxes	20,221	15,004
Other current liabilities	138,003	32,411
Total current liabilities	986,187	924,676
LONG-TERM DEBT, net of current maturities	2,664,122	2,628,989
DEFERRED INCOME TAXES PAYABLE	625,504	623,580
NONCURRENT OPERATING LEASE LIABILITIES	238,572	259,237
OTHER LONG-TERM LIABILITIES	116,036	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, as of June 30, 2020 and December 31, 2019, respectively	694,997	686,806
Retained earnings	2,064,794	2,079,179
Treasury stock, at cost, 31,913,635 and 31,420,179 shares issued, as of June 30, 2020 and December 31, 2019, respectively	(617,136)	(590,971)
Unrealized appreciation on securities	307
Total stockholders' equity	2,142,962	2,175,014
Total liabilities and stockholders' equity	$ 6,773,383	$ 6,657,129