Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 177,708	$ 216,510
Accounts receivable—net	65,732	38,990
Contract revenues in excess of billings	28,918	32,106
Inventories	33,756	34,689
Prepaid expenses and other current assets	43,563	40,398
Total current assets	349,677	362,693
PROPERTY AND EQUIPMENT—Net	400,723	383,042
OPERATING LEASE ASSETS	57,687	65,188
GOODWILL	76,576	76,576
INVENTORIES—Noncurrent	62,725	58,413
OTHER	12,594	12,112
TOTAL	959,982	958,024
LIABILITIES AND EQUITY
Accounts payable	70,756	71,308
Accrued expenses	44,017	52,899
Operating lease liabilities	15,861	19,472
Billings in excess of contract revenues	38,663	32,608
Total current liabilities	169,297	176,287
LONG-TERM DEBT	323,958	323,735
OPERATING LEASE LIABILITIES—Noncurrent	42,058	45,879
DEFERRED INCOME TAXES	58,492	56,466
OTHER	9,567	8,989
Total liabilities	603,372	611,356
COMMITMENTS AND CONTINGENCIES (Note 8)
EQUITY:
Common stock—$.0001 par value; 90,000 authorized, 65,620 and 65,023 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively.	6	6
Additional paid-in capital	303,999	304,757
Retained earnings	49,751	40,937
Accumulated other comprehensive income	2,854	968
Total equity	356,610	346,668
TOTAL	$ 959,982	$ 958,024