Property and Equipment - Summary of Property and Equipment by Classification (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Sep. 30, 2013
Property, Plant and Equipment
Cost	$ 4,151,294	$ 3,746,005
Less: Accumulated depreciation	(565,245)	(581,281)
Drilling and other property and equipment, net	3,586,049	3,164,724
Drilling vessels and equipment
Property, Plant and Equipment
Cost	3,552,698	2,979,503
Construction work in progress
Property, Plant and Equipment
Cost	535,372	715,320
Drill pipe
Property, Plant and Equipment
Cost	27,477	26,743
Office equipment and other
Property, Plant and Equipment
Cost	$ 35,747	$ 24,439