PROPERTY AND EQUIPMENT - Narrative (Details) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended			6 Months Ended
	Dec. 13, 2016 USD ($)	Dec. 05, 2016 drillship	Feb. 28, 2017 rig	Mar. 31, 2017 USD ($) drillship	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) $ / shares	Mar. 31, 2017 USD ($) drillship	Mar. 31, 2016 USD ($) $ / shares
Property, Plant and Equipment
Asset impairment				$ 58,962	$ 708		$ 58,962	$ 65,432
Construction in Progress, Ultra-Deepwater Drillships | Capital Addition Purchase Commitments
Property, Plant and Equipment
Construction in progress, gross				$ 972,000			$ 972,000
Number of drillships with options to delay delivery | drillship				2			2
Wells and Related Equipment and Facilities
Property, Plant and Equipment
Commitments on drilling units under construction							$ 298,000
Atwood Osprey
Property, Plant and Equipment
Insurance recoveries								18,000
Insurance recoveries, net of tax								$ 18,000
Insurance recoveries effect on earnings per share, after tax (in dollars per share) | $ / shares								$ 0.28
Atwood Eagle
Property, Plant and Equipment
Asset impairment							59,000
Impairment, net of tax						$ 57,600
Impairment effect on earnings per share, after tax (in dollars per share) | $ / shares						$ 0.74
Atwood Eagle | Equipment
Property, Plant and Equipment
Asset impairment							49,600
Atwood Eagle | Inventory
Property, Plant and Equipment
Asset impairment							8,400
Atwood Falcon
Property, Plant and Equipment
Asset impairment						$ 64,700
Impairment, net of tax						$ 64,700
Impairment effect on earnings per share, after tax (in dollars per share) | $ / shares						$ 1.00
Atwood Falcon | Equipment
Property, Plant and Equipment
Asset impairment						$ 53,000
Atwood Falcon | Inventory
Property, Plant and Equipment
Asset impairment						$ 11,700
Atwood Admiral and Atwood Archer | Ultra-Deepwater Drillships | Capital Addition Purchase Commitments
Property, Plant and Equipment
Number of drillships with options to delay delivery | drillship		2
Construction in progress, period of delivery delay		2 years
Atwood Archer | Capital Addition Purchase Commitments
Property, Plant and Equipment
Payments for construction projects	$ 125,000
Payment for construction in process, future payment, amount							15,000
Atwood Archer | Capital Addition Purchase Commitments | Final Payment
Property, Plant and Equipment
Commitments on drilling units under construction							$ 165,000
Atwood Admiral
Property, Plant and Equipment
Accelerated delivery notice period (in days)							45 days
Atwood Admiral | Capital Addition Purchase Commitments
Property, Plant and Equipment
Payment for construction in process, future payment, amount							$ 10,000
Atwood Admiral | Capital Addition Purchase Commitments | Final Payment
Property, Plant and Equipment
Commitments on drilling units under construction							$ 83,900
Promissory Note | Ultra-Deepwater Drillships
Property, Plant and Equipment
Stated interest rate				5.00%			5.00%
Woodside Energy Ltd.
Property, Plant and Equipment
Contract Term, Contract Initiation Transaction Costs							$ 1,000
Woodside Energy Ltd. | Atwood Osprey
Property, Plant and Equipment
Contract term, duration of contract			100 days
Woodside Energy Ltd. | Drilling Servicing Contracts | Atwood Osprey
Property, Plant and Equipment
Contract term, duration of contract			550 days
Australia/Southeast Asia [Member]
Property, Plant and Equipment
Number of drilling rigs | rig			3