LONG-TERM DEBT (Schedule of Convertible Notes) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Debt Instrument [Line Items]
Principal amount of convertible notes	$ 338	$ 467
Unamortized discount on convertible notes	(30)	(52)
Net carrying value	308	415
Repurchase of convertible notes	25	31	$ 24
Convertible Notes
Debt Instrument [Line Items]
Unamortized discount on convertible notes	(20)
Contractual interest coupon	26	30	29
Amortization of debt discount	8	9	8
Repurchase of convertible notes	24	5	5
Total	$ 58	$ 44	$ 42
2026 | Convertible Notes
Debt Instrument [Line Items]
Total amortization period for debt discount (in years):	10 years
Remaining amortization period for debt discount (in years):	1 year
Effective interest rates on convertible notes:	7.00%
2027 | Convertible Notes
Debt Instrument [Line Items]
Total amortization period for debt discount (in years):	12 years
Remaining amortization period for debt discount (in years):	4 years
Effective interest rates on convertible notes:	7.70%
2013 | Convertible Notes
Debt Instrument [Line Items]
Total amortization period for debt discount (in years):	8 years
Remaining amortization period for debt discount (in years):	5 years
Effective interest rates on convertible notes:	10.90%