Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash, cash equivalents and restricted cash	$ 49,808	$ 39,719
Accounts receivable, net of allowance of $731 in 2021 and $997 in 2020	191,746	153,511
Inventory	50,827	40,410
Prepaid supplies and other	20,008	39,096
TOTAL CURRENT ASSETS	312,389	272,736
Property and equipment, net	2,136,213	1,939,776
Lease incentive	108,712	126,007
Other assets	95,152	78,112
Goodwill and acquired intangibles	508,357	516,290
Operating lease assets	61,351	68,824
Intangibles	112,383	120,316
Goodwill	395,974	395,974
TOTAL ASSETS	3,222,174	3,001,745
CURRENT LIABILITIES:
Accounts payable	151,064	141,425
Accrued salaries, wages and benefits	58,342	56,506
Accrued expenses	16,117	19,005
Current portion of debt obligations	625	13,746
Current portion of lease obligations	17,292	17,784
Unearned revenue and grants	42,404	53,522
TOTAL CURRENT LIABILITIES	285,844	301,988
Long term debt	1,368,569	1,465,331
Post-retirement obligations	22,379	35,099
Long term lease obligations	44,461	51,128
Other liabilities	47,890	47,963
Stock Warrants	72,667	103,474
Deferred income taxes	197,528	141,265
TOTAL LIABILITIES	2,039,338	2,146,248
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; 150,000,000 shares authorized; 74,199,254 and 59,560,036 shares issued and outstanding in 2021 and 2020, respectively	742	596
Additional paid-in capital	991,650	855,547
Retained earnings	264,906	78,010
Accumulated other comprehensive loss	(74,462)	(78,656)
TOTAL STOCKHOLDERS’ EQUITY	1,182,836	855,497
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 3,222,174	$ 3,001,745