Property and Equipment (Detail) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Property, Plant and Equipment [Line Items]
Equipment	$ 4,537,408	$ 3,972,891
Oil and natural gas properties	122,484	110,749
Buildings	62,887	61,425
Land	11,209	11,074
Property, Plant and Equipment, Gross, Total	4,733,988	4,156,139
Less accumulated depreciation and depletion	(1,708,382)	(1,535,239)
Property and equipment, net	$ 3,025,606	$ 2,620,900

The cumulative amount of depreciation, depletion and amortization (related to property, plant and equipment, but not including land) that has been recognized in the income statement.

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- Definition

Gross amount, as of the balance sheet date, of long-lived, depreciable assets that include building structures held for productive use including any addition, improvement, or renovation to the structure, such as interior masonry, interior flooring, electrical, and plumbing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

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- Definition

Gross amount of fixtures and equipment as of the date of the statement of financial position. Fixtures may include and consist of: machinery, equipment, engines, boilers, incinerators, installed building materials; systems and equipment for the purpose of supplying or distributing heating, cooling, electricity, gas, water, air, or light; antennas, cable, wiring and conduits used in connection with radio, television, security, fire prevention, or fire detection or otherwise used to carry electronic signals; telephone systems and equipment; elevators and related machinery and equipment; fire detection, prevention and extinguishing systems and apparatus; security and access control systems and apparatus; plumbing systems; water heaters, ranges, stoves, microwave ovens, refrigerators, dishwashers, garbage disposers, washers, dryers and other appliances; light fixtures, awnings, storm windows and storm doors; pictures, screens, blinds, shades, curtains and curtain rods; mirrors; cabinets, paneling, rugs and floor and wall coverings; fences, trees and plants; swimming pools; and such other items as defined by the reporting entity.

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Carrying amount as of the balance sheet date of real estate held for productive use. This excludes land held for sale.

+ References

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Oil and Gas properties, gross, carried under the successful effort method.

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Gross amount, at the balance sheet date, of long-lived physical assets used in the normal conduct of business and not intended for resale. This can include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.

+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Tangible assets that are held by an entity for use in the production or supply of goods and services, for rental to others, or for administrative purposes and that are expected to provide economic benefit for more than one year; net of accumulated depreciation. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.

+ References

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-Publisher FASB

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-Publisher FASB

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