PROPERTY AND EQUIPMENT (Property and Equipment by Classification) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Property, Plant and Equipment [Line Items]
Cost	$ 4,568,153	$ 3,746,005
Less: Accumulated depreciation	(601,125)	(581,281)
Drilling and other property and equipment, net	3,967,028	3,164,724	2,537,340
Drilling vessels equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	4,181,774	2,979,503
Construction work in progress [Member]
Property, Plant and Equipment [Line Items]
Cost	319,548	715,320
Drill pipe [Member]
Property, Plant and Equipment [Line Items]
Cost	31,265	26,743
Office equipment and other [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 35,566	$ 24,439