Derivative Financial Instruments - Gains and Losses on Cash Flow Hedge Derivative Contracts Included in the Consolidated Statement of Operations and the Statement of Comprehensive Income (Details) (Designated as Hedging Instrument, Cash Flow Hedging, USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Derivative Instruments, Gain (Loss)
Amount of Gain or (Loss) Recognized in AOCI on Derivative (Effective Portion)	$ (580)	$ 18	$ (1,324)	$ (48)
Amount of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	(539)	(436)	(921)	(874)
Interest expense, net of capitalized interest
Derivative Instruments, Gain (Loss)
Amount of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	(451)	(436)	(805)	(874)
Contract drilling revenues & costs
Derivative Instruments, Gain (Loss)
Amount of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	(88)	0	(116)	0
Interest rate swaps
Derivative Instruments, Gain (Loss)
Amount of Gain or (Loss) Recognized in AOCI on Derivative (Effective Portion)	(457)	18	(435)	(48)
Foreign exchange forward currency contracts
Derivative Instruments, Gain (Loss)
Amount of Gain or (Loss) Recognized in AOCI on Derivative (Effective Portion)	$ (123)	$ 0	$ (889)	$ 0