Drilling And Other Property And Equipment (Summary of Cost and Accumulated Depreciation of Drilling and Other Property and Equipment) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Drilling rigs and equipment	$ 7,352,374	$ 7,431,713
Construction work-in-progress	870,192	504,805
Land and buildings	63,258	60,926
Office equipment and other	54,919	49,035
Cost	8,340,743	8,046,479
Less: accumulated depreciation	(3,505,028)	(3,379,010)
Drilling and other property and equipment, net	$ 4,835,715	$ 4,667,469

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 of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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- Definition

Amount, net of accumulated depreciation, depletion and amortization, of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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