Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 1,863,710	$ 1,789,723
Restricted cash	62,200	71,401
Short-term investment securities	106,375	106,339
Accounts receivable, net	141,254	42,940
Aircraft maintenance deposits, net	45,111	73,134
Income tax receivable	37,714	147,460
Prepaid expenses and other current assets	132,038	124,983
Total current assets	2,388,402	2,355,980
Property and equipment:
Flight equipment	4,257,349	4,177,631
Ground property and equipment	356,344	334,167
Less accumulated depreciation	(781,431)	(680,230)
Total property and equipment, net	3,832,262	3,831,568
Operating lease right-of-use assets	1,598,137	1,417,823
Pre-delivery deposits on flight equipment	443,445	356,262
Long-term aircraft maintenance deposits	50,654	53,158
Deferred heavy maintenance, net	323,105	347,907
Other long-term assets	35,478	36,127
Total assets	8,671,483	8,398,825
Current liabilities:
Accounts payable	55,072	28,454
Air traffic liability	608,136	401,966
Current maturities of long-term debt and finance leases	210,945	384,197
Current maturities of operating leases	144,571	133,791
Deferred salaries, wages and benefits	86,360	0
Other current liabilities	496,095	393,614
Total current liabilities	1,601,179	1,342,022
Long-term debt and finance leases, less current maturities	3,014,958	3,066,635
Operating leases, less current maturities	1,422,139	1,248,519
Deferred income taxes	412,621	439,894
Deferred gains and other long-term liabilities	39,779	52,060
Shareholders’ equity:
Common stock	11	10
Additional paid-in-capital	1,126,031	799,549
Treasury stock, at cost	(75,448)	(74,124)
Retained earnings	1,130,754	1,524,878
Accumulated other comprehensive loss	(541)	(618)
Total shareholders’ equity	2,180,807	2,249,695
Total liabilities and shareholders’ equity	$ 8,671,483	$ 8,398,825