Condensed Balance Sheets (unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 898,457	$ 800,849
Short-term investment securities	101,254	100,937
Accounts receivable, net	52,313	49,323
Aircraft maintenance deposits, net	95,167	175,615
Income tax receivable	69,844	69,844
Prepaid expenses and other current assets	81,806	85,542
Total current assets	1,298,841	1,282,110
Property and equipment:
Flight equipment	2,853,431	2,291,110
Ground property and equipment	161,398	155,166
Less accumulated depreciation	(235,532)	(207,808)
Total property and equipment	2,779,297	2,238,468
Deposits on flight equipment purchase contracts	205,040	253,687
Long-term aircraft maintenance deposits	149,751	150,617
Deferred heavy maintenance, net	138,942	99,915
Other long-term assets	82,560	121,003
Total assets	4,654,431	4,145,800
Current liabilities:
Accounts payable	31,674	22,822
Air traffic liability	357,193	263,711
Current maturities of long-term debt and capital leases	280,281	115,430
Other current liabilities	378,178	262,370
Total current liabilities	1,047,326	664,333
Long-term debt, less current maturities	1,570,926	1,387,498
Deferred income taxes	292,888	308,814
Deferred gains and other long-term liabilities	23,486	22,581
Shareholders’ equity:
Common stock	7	7
Additional paid-in-capital	363,230	360,153
Treasury stock, at cost	(66,813)	(65,854)
Retained earnings	1,424,810	1,469,732
Accumulated other comprehensive loss	(1,429)	(1,464)
Total shareholders’ equity	1,719,805	1,762,574
Total liabilities and shareholders’ equity	$ 4,654,431	$ 4,145,800