BUSINESS SEGMENT INFORMATION - Segment Summary (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Revenues:
Revenues	$ 293,240	$ 439,994	$ 986,412	$ 1,344,254
Operating (loss) income:
Impairment and other charges	71,650		71,650
(Loss) Gain on disposition of assets, net	(1,727)	286	2,910	3,459
Operating (loss) income	(92,639)	54,553	(86,413)	190,380
Interest expense	(8)	(150)	(261)	(368)
Interest income	182	783	1,576	1,643
Other (expense) income , net	(937)	287	(545)	9,786
(Loss) income before income taxes	(93,402)	55,473	(85,643)	201,441
Depreciation and amortization	44,701	42,993	130,087	120,567
Capital expenditures			209,263	199,581
Identifiable assets	1,109,863	1,245,662	1,109,863	1,245,662	$ 1,199,580
Technical Services
Revenues:
Revenues	274,483	421,271	926,596	1,290,186
Operating (loss) income:
Impairment and other charges	69,640
Operating (loss) income	(18,174)	56,209	(15,782)	196,838
Depreciation and amortization			122,827	110,991
Capital expenditures			198,757	194,115
Identifiable assets	963,544	984,397	963,544	984,397
Support Services
Revenues:
Revenues	18,757	18,723	59,816	54,068
Operating (loss) income:
Operating (loss) income	1,632	1,787	8,787	2,075
Depreciation and amortization			7,026	9,247
Capital expenditures			8,546	4,260
Identifiable assets	77,848	77,870	77,848	77,870
Corporate
Operating (loss) income:
Impairment and other charges			2,010
Operating (loss) income	(2,720)	(3,729)	(10,678)	(11,992)
Depreciation and amortization			234	329
Capital expenditures			1,960	1,206
Identifiable assets	$ 68,471	$ 183,395	$ 68,471	$ 183,395