Business Segment Information (Schedule Of Reportable Segments Financial Information) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Operating revenues	$ 161,035	$ 189,247	$ 193,596	$ 261,721	$ 400,911	$ 393,955	$ 359,662	$ 336,756	$ 805,599	$ 1,491,284	$ 1,262,904
Direct operating costs									(642,856)	(1,011,419)	(868,088)
Segment profits	24,992	$ 34,317	$ 37,022	$ 66,412	128,729	$ 129,835	$ 116,732	$ 104,569	162,743	479,865	394,816
Depreciation and amortization									241,471	217,480	209,747
Capital expenditures, (excluding acquisitions)									69,820	311,494	187,515
Identifiable assets	1,161,369				1,597,177				1,161,369	1,597,177	1,543,339
Completion and Remedial Services
Segment Reporting Information [Line Items]
Operating revenues									307,550	698,917	501,137
Direct operating costs									(245,069)	(434,457)	(327,540)
Segment profits									62,481	264,460	173,597
Depreciation and amortization									83,882	74,924	62,609
Capital expenditures, (excluding acquisitions)									22,384	168,017	59,345
Identifiable assets	365,574				514,842				365,574	514,842	432,267
Fluid Services
Segment Reporting Information [Line Items]
Operating revenues									258,597	369,774	343,863
Direct operating costs									(196,155)	(265,105)	(239,154)
Segment profits									62,442	104,669	104,709
Depreciation and amortization									71,280	64,445	63,316
Capital expenditures, (excluding acquisitions)									19,950	71,112	66,992
Identifiable assets	257,036				299,542				257,036	299,542	320,404
Well Servicing
Segment Reporting Information [Line Items]
Operating revenues									217,245	361,683	363,386
Direct operating costs									(184,952)	(270,344)	(265,058)
Segment profits									32,293	91,339	98,328
Depreciation and amortization									60,466	55,131	60,474
Capital expenditures, (excluding acquisitions)									18,732	54,858	39,001
Identifiable assets	233,293				276,696				233,293	276,696	289,017
Contract drilling equipment
Segment Reporting Information [Line Items]
Operating revenues									22,207	60,910	54,518
Direct operating costs									(16,680)	(41,513)	(36,336)
Segment profits									5,527	19,397	18,182
Depreciation and amortization									14,083	12,773	12,815
Capital expenditures, (excluding acquisitions)									2,431	9,311	4,576
Identifiable assets	51,930				60,362				51,930	60,362	59,868
Corporate and Other
Segment Reporting Information [Line Items]
Depreciation and amortization									11,760	10,207	10,533
Capital expenditures, (excluding acquisitions)									6,323	8,196	17,601
Identifiable assets	$ 253,536				$ 445,735				$ 253,536	$ 445,735	$ 441,783