Business Segment Information - Summary of financial information concerning reportable segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenues	$ 728,974	$ 1,263,840	$ 2,337,413
Operating profit (loss)	(238,942)	(156,277)	400,929
Capital expenditures	33,938	167,426	371,502
Depreciation and amortization	217,258	270,977	230,813
Identifiable assets	1,035,452	1,237,094	1,759,358
Operating Segments | Technical Services
Segment Reporting Information [Line Items]
Revenues	679,654	1,175,293	2,180,457
Operating profit (loss)	(203,804)	(132,982)	390,004
Capital expenditures	28,380	155,361	342,932
Depreciation and amortization	191,181	237,778	198,636
Identifiable assets	733,008	976,761	1,514,084
Operating Segments | Support Services
Segment Reporting Information [Line Items]
Revenues	49,320	88,547	156,956
Operating profit (loss)	(26,021)	(2,363)	42,510
Capital expenditures	2,928	11,055	27,148
Depreciation and amortization	25,606	32,697	31,578
Identifiable assets	76,876	108,262	157,688
Corporate
Segment Reporting Information [Line Items]
Revenues
Operating profit (loss)	(17,037)	(14,515)	(16,113)
Capital expenditures	2,630	1,010	1,422
Depreciation and amortization	471	502	599
Identifiable assets	225,568	152,071	87,586
Loss on disposition of assets, net
Segment Reporting Information [Line Items]
Revenues
Operating profit (loss)	7,920	(6,417)	(15,472)
Capital expenditures
Depreciation and amortization
Identifiable assets