Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 47,472	$ 32,699
Accounts receivable, net of allowance of $2,495 in 2018 and $2,445 in 2017	100,186	109,114
Inventory	22,256	22,169
Prepaid supplies and other	13,426	20,521
TOTAL CURRENT ASSETS	183,340	184,503
Property and equipment, net	1,176,520	1,159,962
Lease incentive	76,458	80,684
Other assets	30,852	25,435
Goodwill and acquired intangibles	44,287	44,577
Convertible note hedges	56,046	53,683
Intangibles	7,008	7,298
Goodwill	37,279	37,279
TOTAL ASSETS	1,567,503	1,548,844
CURRENT LIABILITIES:
Accounts payable	96,041	99,728
Accrued salaries, wages and benefits	29,436	40,127
Accrued expenses	10,259	10,455
Current portion of debt obligations	14,846	18,512
Unearned revenue	12,765	15,850
TOTAL CURRENT LIABILITIES	163,347	184,672
Long term debt	515,595	497,246
Convertible note obligations	56,881	54,359
Post-retirement obligations	56,771	61,355
Other liabilities	44,276	45,353
Stock Warrants	214,205	211,136
Deferred income taxes	107,930	99,444
TOTAL LIABILITIES	1,159,005	1,153,565
Commitments and contingencies (Note H)
STOCKHOLDERS’ EQUITY:
Preferred stock, 20,000,000 shares authorized, including 75,000 Series A Junior Participating Preferred Stock	0	0
Common stock, par value $0.01 per share; 85,000,000 shares authorized; 59,080,512 and 59,057,195 shares issued and outstanding in 2018 and 2017, respectively	591	591
Additional paid-in capital	467,570	471,456
Retained earnings (accumulated deficit)	2,644	(13,748)
Accumulated other comprehensive loss	(62,307)	(63,020)
TOTAL STOCKHOLDERS’ EQUITY	408,498	395,279
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 1,567,503	$ 1,548,844