Segment Information (Schedule Of Segment Reporting Information) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 336,072	$ 356,585	$ 367,438	$ 365,274	$ 389,447	$ 378,400	$ 356,901	$ 354,109	$ 1,425,369	$ 1,478,857	$ 1,305,529
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	223,570	231,927	229,532	240,053	248,394	245,832	235,679	240,583	925,082	970,488	889,809
Depreciation, depletion, amortization and accretion	$ 43,741	45,104	51,271	$ 56,343	65,478	$ 69,338	$ 67,862	$ 75,761	196,459	278,439	326,856
General and administrative expenses									268,226	276,468	285,597
Reduction in value of assets		$ 9,628	$ 7,557		$ 322,713				17,185	322,713	10,390
Income (loss) from operations									18,417	(369,251)	(207,123)
Interest income (expense), net									(98,312)	(99,477)	(101,455)
Other expense									(2,484)	(1,678)	(3,299)
Income (loss) from continuing operations before income taxes									(82,379)	(470,406)	(311,877)
Drilling Products And Services [Member]
Segment Reporting Information [Line Items]
Revenues									411,573	383,719	293,690
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)									154,503	148,019	128,381
Depreciation, depletion, amortization and accretion									83,999	112,111	131,394
General and administrative expenses									60,094	53,688	51,265
Reduction in value of assets											1,356
Income (loss) from operations									112,977	69,901	(18,706)
Income (loss) from continuing operations before income taxes									112,977	69,901	(18,706)
Onshore Completion And Workover Services [Member]
Segment Reporting Information [Line Items]
Revenues									341,297	406,248	366,636
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)									274,162	315,291	282,695
Depreciation, depletion, amortization and accretion									33,699	68,183	81,238
General and administrative expenses									25,621	24,386	34,856
Reduction in value of assets									8,122	227,801	919
Income (loss) from operations									(307)	(229,413)	(33,072)
Income (loss) from continuing operations before income taxes									(307)	(229,413)	(33,072)
Production Services [Member]
Segment Reporting Information [Line Items]
Revenues									405,830	418,525	372,781
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)									328,527	342,420	303,256
Depreciation, depletion, amortization and accretion									51,370	66,993	78,999
General and administrative expenses									29,622	41,499	48,655
Reduction in value of assets									2,055	92,252
Income (loss) from operations									(5,744)	(124,639)	(58,129)
Income (loss) from continuing operations before income taxes									(5,744)	(124,639)	(58,129)
Technical Solutions [Member]
Segment Reporting Information [Line Items]
Revenues									266,669	270,365	272,422
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)									167,890	164,758	175,477
Depreciation, depletion, amortization and accretion									22,665	25,653	29,506
General and administrative expenses									59,587	57,600	51,679
Reduction in value of assets									7,008		8,115
Income (loss) from operations									9,519	22,354	7,645
Interest income (expense), net									4,172	3,915	3,567
Income (loss) from continuing operations before income taxes									13,691	26,269	11,212
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion, amortization and accretion									4,726	5,499	5,719
General and administrative expenses									93,302	99,295	99,142
Reduction in value of assets										2,660
Income (loss) from operations									(98,028)	(107,454)	(104,861)
Interest income (expense), net									(102,484)	(103,392)	(105,022)
Other expense									(2,484)	(1,678)	(3,299)
Income (loss) from continuing operations before income taxes									$ (202,996)	$ (212,524)	$ (213,182)