Segment Information (Schedule Of Identifiable Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Assets	$ 1,993,230	$ 2,215,962	$ 3,110,225
Drilling Products And Services [Member]
Segment Reporting Information [Line Items]
Assets	659,621	587,264	662,968
Onshore Completion And Workover Services [Member]
Segment Reporting Information [Line Items]
Assets	467,697	808,037	1,501,214
Production Services [Member]
Segment Reporting Information [Line Items]
Assets	421,848	434,430	512,256
Technical Solutions [Member]
Segment Reporting Information [Line Items]
Assets	377,627	340,161	377,549
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Assets	$ 66,437	$ 46,070	$ 56,238