Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash, cash equivalents and restricted cash	$ 84,909	$ 39,719
Accounts receivable, net of allowance of $890 in 2021 and $997 in 2020	176,146	153,511
Inventory	44,501	40,410
Prepaid supplies and other	27,931	39,096
TOTAL CURRENT ASSETS	333,487	272,736
Property and equipment, net	2,097,256	1,939,776
Lease incentive	114,510	126,007
Other assets	90,675
Goodwill and acquired intangibles	511,001	516,290
Operating lease assets	63,925	68,824
Intangibles	115,027	120,316
Goodwill	395,974	395,974
TOTAL ASSETS	3,210,854	3,001,745
CURRENT LIABILITIES:
Accounts payable	172,286	141,425
Accrued salaries, wages and benefits	58,888	56,506
Accrued expenses	18,213	19,005
Current portion of debt obligations	622	13,746
Current portion of lease obligations	16,889	17,784
Unearned revenue and grants	68,970	53,522
TOTAL CURRENT LIABILITIES	335,868	301,988
Long term debt	1,398,470	1,465,331
Post-retirement obligations	25,626	35,099
Long term lease obligations	47,192	51,128
Other liabilities	47,183	47,963
Stock Warrants	63,085	103,474
Deferred income taxes	178,703	141,265
TOTAL LIABILITIES	2,096,127	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; 74,202,815 and 59,560,036 shares issued and outstanding in 2021 and 2020, respectively	742	596
Additional paid-in capital	989,611	855,547
Retained earnings	200,234	78,010
Accumulated other comprehensive loss	(75,860)	(78,656)
TOTAL STOCKHOLDERS’ EQUITY	1,114,727	855,497
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 3,210,854	$ 3,001,745