PROPERTY AND EQUIPMENT (Narrative) (Details) $ / shares in Units, $ in Thousands				1 Months Ended				12 Months Ended
	May. 18, 2015 USD ($)	Feb. 06, 2015 USD ($) period drillship	Oct. 31, 2014 USD ($)	Aug. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Apr. 30, 2014 USD ($)	Jan. 31, 2014 USD ($)	Sep. 30, 2015 USD ($) $ / shares	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)
Property, Plant and Equipment [Line Items]
Asset impairment								$ 60,777	$ 0	$ 0
Proceeds from Sale of Property, Plant, and Equipment								(4,402)	61,516	147
Other Operating Income (Expense), Net								0	1,864	0
Gain (Loss) on Disposition of Property Plant Equipment								(15,303)	$ 34,139	$ (971)
Atwood Southern Cross [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets to be Disposed of, Net of Tax								$ 7,100
Impairment Effect on Earnings Per Share, after Tax | $ / shares								$ 0.11
Proceeds from Sale of Property, Plant, and Equipment					$ 2,100
Other Operating Income (Expense), Net					$ 2,000
Gain (Loss) on Disposition of Property Plant Equipment								$ (8,000)
Standard Jackup Drilling Unit [Member]
Property, Plant and Equipment [Line Items]
Carrying value of equipment and related inventory							$ 20,500
Proceeds from Sale of Property, Plant, and Equipment							$ 55,400
Semisubmersible Tender Assist Drilling Rig [Member]
Property, Plant and Equipment [Line Items]
Carrying value of equipment and related inventory						$ 2,000
Proceeds from Sale of Property, Plant, and Equipment						$ 4,000
Daewood Shipbuilding [Member]
Property, Plant and Equipment [Line Items]
Construction in Progress, Gross								675,000
Atwood Admiral [Member]
Property, Plant and Equipment [Line Items]
Number Of Drillships With Options To Delay Delivery | drillship		2
Number Of Six-Month Periods In Option To Postpone Delivery | period		2
Atwood Hunter [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets to be Disposed of, Net of Tax								$ 5,500
Impairment Effect on Earnings Per Share, after Tax | $ / shares								$ 0.08
Proceeds from Sale of Property, Plant, and Equipment				$ 2,900
Cost Related To Sale Of Property Plant And Equipment				$ 8,700
Gain (Loss) on Disposition of Property Plant Equipment								$ (5,500)
Capital Addition Purchase Commitments [Member] | Construction in Progress, Newbuild Drilling Units [Member]
Property, Plant and Equipment [Line Items]
Interest Rate to be added as Part of the Milestone payment			3.50%
Capital Addition Purchase Commitments [Member] | Daewood Shipbuilding [Member]
Property, Plant and Equipment [Line Items]
Commitments on drilling units under construction								575,000
Atwood Hunter [Member]
Property, Plant and Equipment [Line Items]
Asset impairment								60,800
Impairment of Long-Lived Assets to be Disposed of, Net of Tax								$ 56,100
Impairment Effect on Earnings Per Share, after Tax | $ / shares								$ 0.86
Atwood Hunter [Member] | Equipment [Member]
Property, Plant and Equipment [Line Items]
Asset impairment								$ 48,000
Atwood Hunter [Member] | Inventories [Member]
Property, Plant and Equipment [Line Items]
Asset impairment								8,400
Milestone Payment No 1 [Member] | Capital Addition Purchase Commitments [Member] | Atwood Admiral [Member]
Property, Plant and Equipment [Line Items]
Commitments on drilling units under construction	$ 150,000	$ 146,000	$ 50,000					147,000
Payments for Construction in Process	150,000
Milestone Payment No 1 [Member] | Capital Addition Purchase Commitments [Member] | Atwood Archer [Member]
Property, Plant and Equipment [Line Items]
Commitments on drilling units under construction	$ 150,000	205,000						$ 358,000
Milestone Payment No 2 [Member] | Capital Addition Purchase Commitments [Member] | Atwood Admiral [Member]
Property, Plant and Equipment [Line Items]
Commitments on drilling units under construction		152,000	$ 25,000
Milestone Payment No 2 [Member] | Capital Addition Purchase Commitments [Member] | Atwood Archer [Member]
Property, Plant and Equipment [Line Items]
Commitments on drilling units under construction		$ 153,000