BUSINESS SEGMENT INFORMATION - Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Revenues:
Revenues	$ 476,668	$ 284,624
Operating income:
Operating income	90,657	23,035
Interest expense	(72)	(178)
Interest income	1,855	15
Other income, net	761	504
Income before income taxes	93,201	23,376
Depreciation and amortization	24,125	19,466
Capital expenditures	65,300	19,084
Identifiable assets	1,187,830	891,168	$ 1,129,013
Technical Services
Revenues:
Revenues	451,991	266,349
Operating income:
Operating income	103,533	21,811
Depreciation and amortization	22,008	16,974
Capital expenditures	63,002	16,624
Identifiable assets	851,689	616,961
Support Services
Revenues:
Revenues	24,677	18,275
Operating income:
Operating income	6,644	2,780
Depreciation and amortization	2,104	2,427
Capital expenditures	1,313	2,410
Identifiable assets	82,530	74,021
Pension settlement charge
Operating income:
Operating income	(17,375)
Corporate
Operating income:
Operating income	(5,081)	(4,510)
Depreciation and amortization	13	65
Capital expenditures	985	50
Identifiable assets	253,611	200,186
Gain on disposition of assets, net.
Operating income:
Operating income	$ 2,936	$ 2,954