Property And Equipment (Schedule Of Property And Equipment) (Details) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Property And Equipment [Abstract]
Oil and natural gas properties	$ 1,130,838,000	$ 1,035,754,000
Office furniture and fixtures	3,774,000	3,692,000
Building	3,926,000	4,049,000
Land	260,000	283,000
Total property and equipment	1,138,798,000	1,043,778,000
Accumulated depletion, depreciation, amortization and impairment	(596,530,000)	(575,142,000)
Property and equipment, net	$ 542,268,000	$ 468,636,000

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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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.

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- Definition

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.

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- Definition

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.

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