Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
CURRENT ASSETS:
Cash and cash equivalents	$ 32,699	$ 16,358
Accounts receivable, net of allowance of $2,445 in 2017 and $1,264 in 2016	109,114	77,247
Inventory	22,169	19,925
Prepaid supplies and other	20,521	19,123
TOTAL CURRENT ASSETS	184,503	132,653
Property and equipment, net	1,159,962	1,000,992
Lease incentive	80,684	54,730
Other assets	25,435	25,369
Goodwill and acquired intangibles	44,577	45,586
Convertible note hedges	53,683	0
Intangibles	7,298	8,453
Goodwill	37,279	37,133
TOTAL ASSETS	1,548,844	1,259,330
CURRENT LIABILITIES:
Accounts payable	99,728	60,704
Accrued salaries, wages and benefits	40,127	37,044
Accrued expenses	10,455	10,324
Current portion of debt obligations	18,512	29,306
Unearned revenue	15,850	18,407
TOTAL CURRENT LIABILITIES	184,672	155,785
Long term debt	497,246	429,415
Convertible note obligations	54,359	0
Post-retirement obligations	61,355	77,713
Other liabilities	45,353	52,542
Stock Warrants	211,136	89,441
Deferred income taxes	99,444	122,532
TOTAL LIABILITIES	1,153,565	927,428
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; 59,057,195 and 59,461,291 shares issued and outstanding in 2017 and 2016, respectively	591	595
Additional paid-in capital	471,456	443,416
Accumulated deficit	(13,748)	(32,243)
Accumulated other comprehensive loss	(63,020)	(79,866)
TOTAL STOCKHOLDERS’ EQUITY	395,279	331,902
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 1,548,844	$ 1,259,330