RETIREMENT MEDICAL PLANS (Details 4) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss), Net Of Tax [Roll Forward]
Deferred tax impact	$ (5)	$ (2)	$ (12)
U.S. Retiree Medical Plan
Accumulated Other Comprehensive Income (Loss), Net Of Tax [Roll Forward]
Balance, beginning	129	150
Net actuarial gain for the year	(19)	(3)
Curtailment gain		(16)
Recognized prior service costs due to curtailment		15
Amortization for the year	(21)	(16)
Deferred tax impact		(1)
Balance, ending	89	129	150
U.S. Retiree Medical Plan | Net Actuarial Loss
Accumulated Other Comprehensive Income (Loss), Net Of Tax [Roll Forward]
Balance, beginning	142	169
Net actuarial gain for the year	(19)	(3)
Curtailment gain		0
Recognized prior service costs due to curtailment		0
Amortization for the year	(22)	(23)
Deferred tax impact		(1)
Balance, ending	101	142	169
U.S. Retiree Medical Plan | Prior Service Cost (Benefit)
Accumulated Other Comprehensive Income (Loss), Net Of Tax [Roll Forward]
Balance, beginning	(13)	(19)
Net actuarial gain for the year	0	0
Curtailment gain		(16)
Recognized prior service costs due to curtailment		15
Amortization for the year	1	7
Deferred tax impact		0
Balance, ending	$ (12)	$ (13)	$ (19)