Business Segment Information (Schedule Of Segment Reporting Information) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting Information [Line Items]
Operating revenues	$ 354,359	$ 345,987	$ 296,855	$ 246,054	$ 212,880	$ 197,261	$ 175,132	$ 142,966	$ 1,243,255	$ 728,239	$ 526,627
Direct operating costs									(766,112)	(506,860)	(389,588)
Segment profits	138,990	136,647	111,538	89,968	71,807	59,051	53,588	36,933	477,143	221,379	137,039
Depreciation and amortization									154,341	135,001	132,520
Capital expenditures, (excluding acquisitions)									221,839	63,579	43,367
Identifiable assets	1,459,928				1,029,813				1,459,928	1,029,813	1,039,541
Completion And Remedial Services [Member]
Segment Reporting Information [Line Items]
Operating revenues									537,134	261,436	134,818
Direct operating costs									(297,276)	(156,573)	(95,287)
Segment profits									239,858	104,863	39,531
Depreciation and amortization									45,651	33,538	31,313
Capital expenditures, (excluding acquisitions)									57,928	15,795	10,247
Identifiable assets	398,664				215,503				398,664	215,503	194,988
Fluid Services [Member]
Segment Reporting Information [Line Items]
Operating revenues									332,010	241,164	214,822
Direct operating costs									(211,959)	(178,152)	(159,079)
Segment profits									120,051	63,012	55,743
Depreciation and amortization									42,612	38,745	37,594
Capital expenditures, (excluding acquisitions)									51,543	18,247	12,303
Identifiable assets	241,720				185,057				241,720	185,057	195,107
Well Servicing [Member]
Segment Reporting Information [Line Items]
Operating revenues									333,057	204,872	160,614
Direct operating costs									(228,723)	(156,885)	(121,618)
Segment profits									104,334	47,987	38,996
Depreciation and amortization									48,016	50,530	49,005
Capital expenditures, (excluding acquisitions)									46,805	23,797	16,037
Identifiable assets	280,992				248,441				280,992	248,441	244,556
Contract Drilling [Member]
Segment Reporting Information [Line Items]
Operating revenues									41,054	20,767	16,373
Direct operating costs									(28,154)	(15,250)	(13,604)
Segment profits									12,900	5,517	2,769
Depreciation and amortization									9,994	5,171	7,237
Capital expenditures, (excluding acquisitions)									53,112	2,435	2,368
Identifiable assets	77,402				28,375				77,402	28,375	41,320
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization									8,068	7,017	7,371
Capital expenditures, (excluding acquisitions)									12,451	3,305	2,412
Identifiable assets	$ 461,150				$ 352,437				$ 461,150	$ 352,437	$ 363,570