Property And Equipment (Property And Equipment By Classification) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Sep. 30, 2011
Property, Plant and Equipment [Line Items]
Net book value	$ 2,046,214	$ 1,887,321
Drilling Vessels And Related Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	2,489,323	2,315,419
Accumulated depreciation	(450,544)	(435,577)
Net book value	2,038,779	1,879,842
Drill Pipe [Member]
Property, Plant and Equipment [Line Items]
Cost	18,390	18,182
Accumulated depreciation	(14,181)	(13,885)
Net book value	4,209	4,297
Furniture And Other [Member]
Property, Plant and Equipment [Line Items]
Cost	9,064	8,800
Accumulated depreciation	(5,838)	(5,618)
Net book value	$ 3,226	$ 3,182

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, 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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