Condensed Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 1,110,797	$ 1,004,733
Short-term investment securities	104,228	102,789
Accounts receivable, net	78,125	47,660
Aircraft maintenance deposits, net	124,585	106,901
Prepaid expenses and other current assets	102,952	83,383
Total current assets	1,520,687	1,345,466
Property and equipment:
Flight equipment	3,514,104	3,257,215
Ground property and equipment	215,774	191,661
Less accumulated depreciation	(367,712)	(332,864)
Total property and equipment	3,362,166	3,116,012
Operating lease right-of-use assets	1,057,846	0
Pre-delivery deposits on flight equipment	289,902	236,775
Long-term aircraft maintenance deposits	84,507	138,738
Deferred heavy maintenance, net	309,555	249,010
Other long-term assets	38,118	79,456
Total assets	6,662,781	5,165,457
Current liabilities:
Accounts payable	43,848	39,320
Air traffic liability	402,990	291,981
Current maturities of long-term debt and finance leases	270,407	163,557
Current maturities of operating leases	114,877	0
Other current liabilities	379,041	339,677
Total current liabilities	1,211,163	834,535
Long-term debt and finance leases, less current maturities	2,025,183	2,024,774
Operating leases, less current maturities	915,288	0
Deferred income taxes	399,765	355,141
Deferred gains and other long-term liabilities	16,355	22,503
Shareholders’ equity:
Common stock	7	7
Additional paid-in-capital	377,639	371,225
Treasury stock, at cost	(72,264)	(67,016)
Retained earnings	1,790,509	1,625,481
Accumulated other comprehensive income (loss)	(864)	(1,193)
Total shareholders’ equity	2,095,027	1,928,504
Total liabilities and shareholders’ equity	$ 6,662,781	$ 5,165,457