Segment Information (Schedule Of Identifiable Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Assets	$ 1,501,079	$ 1,993,230	$ 2,215,962
Drilling Products And Services [Member]
Segment Reporting Information [Line Items]
Assets	557,469	659,621	587,264
Onshore Completion And Workover Services [Member]
Segment Reporting Information [Line Items]
Assets	183,065	467,697	808,037
Production Services [Member]
Segment Reporting Information [Line Items]
Assets	368,185	421,848	434,430
Technical Solutions [Member]
Segment Reporting Information [Line Items]
Assets	260,339	377,627	340,161
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Assets	$ 132,021	$ 66,437	$ 46,070