BUSINESS SEGMENT INFORMATION - Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Revenues	$ 188,757	$ 89,300	$ 371,367	$ 333,077
Operating income (loss):
Operating loss	(1,220)	(37,530)	(11,741)	(256,237)
Impairment and Other Charges (1)	0	(1,639)	0	(207,175)
Gain on disposition of assets, net	3,111	3,194	4,571	4,013
Interest expense	103	71	483	184
Interest income	14	68	32	402
Other income (expense), net	616	(1,481)	1,123	(1,789)
Loss before income taxes	(693)	(39,014)	(11,069)	(257,808)
Depreciation and amortization	17,896	19,573	35,669	58,866
Capital expenditures			25,875	38,659
Identifiable assets	790,206	782,868	790,206	782,868
Technical Services
Revenues:
Revenues	176,119	80,532	348,760	308,232
Operating income (loss):
Operating loss	1,428	(34,100)	(4,334)	(46,307)
Depreciation and amortization			31,189	54,615
Capital expenditures			21,295	31,296
Identifiable assets	485,058	474,670	485,058	474,670
Support Services
Revenues:
Revenues	12,638	8,768	22,607	24,845
Operating income (loss):
Operating loss	(2,402)	(1,846)	(5,298)	(299)
Depreciation and amortization			4,344	4,111
Capital expenditures			4,347	7,027
Identifiable assets	73,815	62,867	73,815	62,867
Corporate
Operating income (loss):
Operating loss	(3,357)	(3,139)	(6,680)	(6,469)
Impairment and Other Charges (1)	541
Depreciation and amortization			136	140
Capital expenditures			233	336
Identifiable assets	$ 231,333	$ 245,331	$ 231,333	$ 245,331