Property and Equipment (A Summary of Property and Equipment by Classification) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013
Property, Plant and Equipment [Line Items]
Cost	$ 4,196,859	$ 3,746,005
Less: Accumulated depreciation	(613,592)	(581,281)
Drilling and other property and equipment, net	3,583,267	3,164,724
Drilling vessels and equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	3,632,897	2,979,503
Construction work in progress [Member]
Property, Plant and Equipment [Line Items]
Cost	501,486	715,320
Drill pipe [Member]
Property, Plant and Equipment [Line Items]
Cost	32,804	26,743
Office equipment and other [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 29,672	$ 24,439