Business Segment and Entity wide Disclosures - Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Revenues	$ 598,302	$ 1,222,409	$ 1,721,005
Operating (loss) gain:
Operating (loss) profit	(309,635)	(114,288)	210,030
Capital expenditures	65,065	250,629	242,610
Depreciation and amortization	95,530	170,409	163,120
Identifiable assets	790,505	1,053,218	1,199,580
Impairment and other charges	217,493	82,273
Pension settlement loss (3)	(4,660)
Technical Services
Revenues:
Revenues	556,488	1,145,554	1,647,213
Operating (loss) gain:
Operating (loss) profit	(82,525)	(32,993)	216,703
Capital expenditures	54,327	237,950	230,262
Depreciation and amortization	80,877	154,776	150,508
Identifiable assets	499,764	848,264	925,305
Impairment and other charges	212,292	80,263
Support Services
Revenues:
Revenues	41,814	76,855	73,792
Operating (loss) gain:
Operating (loss) profit	(6,714)	10,016	4,612
Capital expenditures	10,224	10,330	10,364
Depreciation and amortization	14,377	15,328	12,174
Identifiable assets	64,457	72,351	78,413
Impairment and other charges
Operating (loss) gain:
Operating (loss) profit	(217,493)	(82,273)
Corporate
Operating (loss) gain:
Operating (loss) profit	(12,426)	(12,745)	(14,629)
Capital expenditures	514	2,349	1,984
Depreciation and amortization	276	305	438
Identifiable assets	226,284	132,603	195,862
Impairment and other charges		2,010
Gain (loss) on disposition of assets, net
Operating (loss) gain:
Operating (loss) profit	$ 9,523	$ 3,707	$ 3,344