Condensed Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 812,362	$ 800,849
Short-term investment securities	101,714	100,937
Accounts receivable, net	58,547	49,323
Aircraft maintenance deposits, net	107,252	175,615
Income tax receivable	70,672	69,844
Prepaid expenses and other current assets	79,788	85,542
Total current assets	1,230,335	1,282,110
Property and equipment:
Flight equipment	2,911,378	2,291,110
Ground property and equipment	168,039	155,166
Less accumulated depreciation	(261,314)	(207,808)
Total property and equipment	2,818,103	2,238,468
Deposits on flight equipment purchase contracts	240,224	253,687
Long-term aircraft maintenance deposits	141,183	150,617
Deferred heavy maintenance, net	172,799	99,915
Other long-term assets	79,081	121,003
Total assets	4,681,725	4,145,800
Current liabilities:
Accounts payable	50,310	22,822
Air traffic liability	357,645	263,711
Current maturities of long-term debt and capital leases	145,865	115,430
Other current liabilities	346,407	262,370
Total current liabilities	900,227	664,333
Long-term debt, less current maturities	1,731,766	1,387,498
Deferred income taxes	295,601	308,814
Deferred gains and other long-term liabilities	20,630	22,581
Shareholders’ equity:
Common stock	7	7
Additional paid-in-capital	365,536	360,153
Treasury stock, at cost	(66,840)	(65,854)
Retained earnings	1,436,064	1,469,732
Accumulated other comprehensive income (loss)	(1,266)	(1,464)
Total shareholders’ equity	1,733,501	1,762,574
Total liabilities and shareholders’ equity	$ 4,681,725	$ 4,145,800