Revenue (Disaggregation Of Revenues, By Type) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total Revenues	$ 851,307	$ 1,425,369	$ 1,478,857
Drilling Products And Services [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	281,397	411,573	383,719
Production Services [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	276,329	405,830	418,525
Technical Solutions [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	162,783	266,669	270,365
Services [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	467,548	885,252	933,029
Services [Member] | Drilling Products And Services [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	45,226	69,958	54,997
Services [Member] | Onshore Completion and Workover Services [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	118,948	303,542	364,500
Services [Member] | Production Services [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	215,812	348,168	352,590
Services [Member] | Technical Solutions [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	87,562	163,584	160,942
Rentals [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	241,232	376,247	380,296
Rentals [Member] | Drilling Products And Services [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	198,725	291,975	281,750
Rentals [Member] | Onshore Completion and Workover Services [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	11,850	37,755	41,748
Rentals [Member] | Production Services [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	21,462	32,402	36,568
Rentals [Member] | Technical Solutions [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	9,195	14,115	20,230
Product Sales [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	142,527	163,870	165,532
Product Sales [Member] | Drilling Products And Services [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	37,446	49,640	46,972
Product Sales [Member] | Production Services [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	39,055	25,260	29,367
Product Sales [Member] | Technical Solutions [Member]
Disaggregation of Revenue [Line Items]
Total Revenues	$ 66,026	$ 88,970	$ 89,193