Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 31,704	$ 32,699
Accounts receivable, net of allowance of $1,130 in 2018 and $2,445 in 2017	100,805	109,114
Inventory	24,147	22,169
Prepaid supplies and other	13,017	20,521
TOTAL CURRENT ASSETS	169,673	184,503
Property and equipment, net	1,200,997	1,159,962
Lease incentive	72,232	80,684
Other assets	30,573	25,435
Goodwill and acquired intangibles	43,999	44,577
Convertible note hedges	0	53,683
Intangibles	6,720	7,298
Goodwill	37,279	37,279
TOTAL ASSETS	1,517,474	1,548,844
CURRENT LIABILITIES:
Accounts payable	85,691	99,728
Accrued salaries, wages and benefits	34,189	40,127
Accrued expenses	10,833	10,455
Current portion of debt obligations	14,860	18,512
Unearned revenue	15,022	15,850
TOTAL CURRENT LIABILITIES	160,595	184,672
Long term debt	505,853	497,246
Convertible note obligations	0	54,359
Post-retirement obligations	53,032	61,355
Other liabilities	45,417	45,353
Stock Warrants	203,426	211,136
Deferred income taxes	113,571	99,444
TOTAL LIABILITIES	1,081,894	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; 110,000,000 shares authorized; 59,080,387 and 59,057,195 shares issued and outstanding in 2018 and 2017, respectively	591	591
Additional paid-in capital	469,412	471,456
Retained earnings (accumulated deficit)	27,278	(13,748)
Accumulated other comprehensive loss	(61,701)	(63,020)
TOTAL STOCKHOLDERS’ EQUITY	435,580	395,279
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 1,517,474	$ 1,548,844