Chapter 11 Reorganization (Schedule Of Chapter 11 Reorganization Income Statement) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Total revenues	$ 851,307	$ 1,425,369	$ 1,478,857
Costs and expenses:
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	580,129	925,082	970,488
Depreciation, depletion, amortization and accretion	146,793	196,459	278,439
General and administrative expenses	222,465	268,226	276,468
Restructuring expense	47,055
Reduction in value of assets	26,897	17,185	322,713
Income (loss) from operations	(172,032)	18,417	(369,251)
Other income (expense):
Interest expense, net (contractual interest $95.8 million)	(92,399)	(98,312)	(99,477)
Reorganization expenses	(21,616)
Other income (expense)	(9,229)	(2,484)	(1,678)
Loss from continuing operations before income taxes	(295,276)	(82,379)	(470,406)
Income taxes	(13,928)	(4,626)	(43,003)
Net loss from continuing operations	(281,348)	(77,753)	(427,403)
Loss from discontinued operations, net of income tax	(114,882)	(177,968)	(430,712)
Net loss	$ (396,230)	$ (255,721)	$ (858,115)
Basic and diluted loss per share:
Net loss from continuing operations	$ (18.98)	$ (5.05)	$ (27.69)
Loss from discontinued operations	(7.75)	(11.56)	(27.90)
Net loss	$ (26.73)	$ (16.61)	$ (55.59)
Services [Member]
Revenues:
Total revenues	$ 467,548	$ 885,252	$ 933,029
Costs and expenses:
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	388,319	698,150	699,322
Depreciation, depletion, amortization and accretion	80,334	121,805	175,417
Rentals [Member]
Revenues:
Total revenues	241,232	376,247	380,296
Costs and expenses:
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	102,571	128,695	136,135
Depreciation, depletion, amortization and accretion	41,003	59,189	71,661
Product Sales [Member]
Revenues:
Total revenues	142,527	163,870	165,532
Costs and expenses:
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	89,239	98,237	135,031
Depreciation, depletion, amortization and accretion	25,456	$ 15,465	$ 31,361
Reorganization, Chapter 11, Plan Effect Adjustment [Member]
Revenues:
Total revenues	652,860
Costs and expenses:
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	435,341
Depreciation, depletion, amortization and accretion	112,395
General and administrative expenses	185,236
Restructuring expense	47,055
Reduction in value of assets	21,049
Income (loss) from operations	(148,216)
Other income (expense):
Interest expense, net (contractual interest $95.8 million)	(93,132)
Reorganization expenses	(21,616)
Other income (expense)	(555)
Loss from continuing operations before income taxes	(263,519)
Income taxes	(1,155)
Net loss from continuing operations	(262,364)
Loss from discontinued operations, net of income tax	(114,882)
Net loss	(377,246)
Reorganization, Chapter 11, Plan Effect Adjustment [Member] | Services [Member]
Revenues:
Total revenues	627,070
Costs and expenses:
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	421,295
Reorganization, Chapter 11, Plan Effect Adjustment [Member] | Rentals [Member]
Revenues:
Total revenues	25,790
Costs and expenses:
Cost or revenues (exclusive of depreciation, depletion, amortization and accretion)	$ 14,046