Financing Arrangements (Narrative) (Details) - USD ($)					3 Months Ended		9 Months Ended
	May. 29, 2015	May. 15, 2014	May. 15, 2014	Feb. 05, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 05, 2015	Mar. 31, 2015	Sep. 30, 2014	Aug. 20, 2014
Debt Instrument [Line Items]
Gains (Losses) on Extinguishment of Debt					$ (6,000,000)	$ (1,000,000)	$ (6,000,000)	$ (5,000,000)
Long-term Debt, Gross					$ 6,034,000,000		$ 6,034,000,000
Debt, Weighted Average Interest Rate					7.30%		7.30%				6.90%
Sale Leaseback Transaction, Financing Capacity												$ 24,000,000
Proceeds from sale-leaseback transactions							$ 15,000,000	0
9.75% senior unsecured cash pay notes due 2015
Debt Instrument [Line Items]
Debt Instrument Prepayment Percentage Of Face Value		100.00%
Secured Debt
Debt Instrument [Line Items]
Gains (Losses) on Extinguishment of Debt								(4,000,000)
Debt Issuance Cost								2,000,000
Secured Debt | Senior Secured Multi-Currency Asset-Based Revolver
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity					$ 200,000,000		200,000,000			$ 150,000,000
Letters of Credit Outstanding, Amount					145,000,000		145,000,000				$ 79,000,000
Long-term Debt					40,000,000		40,000,000				40,000,000
Proceeds from borrowings on revolving loans under the Senior Secured Credit Agreement							0	40,000,000
Secured Debt | Senior Secured Multi-Currency Asset-Based Revolver | Base Rate Borrowings
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity					335,000,000		$ 335,000,000
Debt Instrument, Basis Spread on Variable Rate							0.75%
Secured Debt | Senior Secured Multi-Currency Asset-Based Revolver | LIBOR Borrowings
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate							1.75%
Secured Debt | Letter of Credit
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity					40,000,000		$ 40,000,000				207,000,000
Secured Debt | Senior Secured Term B-3 Loans
Debt Instrument [Line Items]
Line Of Credit Facility, Additional Borrowing Capacity							30,000,000
Letters of Credit Outstanding, Amount					0		0
Proceeds from borrowings on revolving loans under the Senior Secured Credit Agreement							20,000,000	0
Line of Credit Facility, Remaining Borrowing Capacity					81,000,000		81,000,000
Secured Debt | Senior Secured Term B-3 Loans | Base Rate Borrowings
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity					150,000,000		150,000,000
Secured Debt | Senior Secured Multi-Currency Revolver
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity									$ 18,000,000	$ 200,000,000
Letters of Credit Outstanding, Amount					$ 0		0				0
Proceeds from borrowings on revolving loans under the Senior Secured Credit Agreement			$ 100,000,000				50,000,000	100,000,000
Secured Debt | Senior secured term B-4 loans
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt	$ 2,125,000,000						2,100,000,000	0
Debt Instrument, Interest Rate, Base Rate	2.00%
Secured Debt | Senior secured term B-4 loans | Base Rate Borrowings
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Base Rate	4.25%
Secured Debt | Senior secured term B-4 loans | LIBOR Borrowings
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	5.25%
Secured Debt | Senior Secured Term B-6 Loans
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt				$ 1,138,000,000			$ 0	$ 1,136,000,000
Unsecured Debt | 10.125%/10.875% senior unsecured PIK toggle notes due 2015
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					10.875%		10.875%
Long-term Debt		$ 92,000,000	92,000,000
Unsecured Debt | 9.75% senior unsecured cash pay notes due 2015
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					9.75%		9.75%
Long-term Debt		$ 58,000,000	58,000,000
Unsecured Debt | Senior Unsecured Cash Interest Notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					10.125%		10.125%
Other current liabilities
Debt Instrument [Line Items]
Capital lease obligations					$ 59,000,000		$ 59,000,000				59,000,000
Base Rate [Member] | Secured Debt | Senior secured term B-4 loans
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Base Rate	0.50%
London Interbank Offered Rate (LIBOR) | Secured Debt | Senior secured term B-4 loans
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Base Rate	1.00%
Unsecured Debt
Debt Instrument [Line Items]
Extinguishment of debt, amount			150,000,000
Repayments of debt			$ 10,000,000
Avaya Pivate Cloud Services business | Other current liabilities
Debt Instrument [Line Items]
Capital lease obligations					45,000,000		45,000,000				40,000,000
Principal Amount
Debt Instrument [Line Items]
Long-term Debt					6,034,000,000		6,034,000,000				6,044,000,000
Principal Amount | Variable rate senior secured multi-currency revolver
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure					18,000,000		18,000,000				90,000,000
Principal Amount | Secured Debt | Senior Secured Multi-Currency Asset-Based Revolver
Debt Instrument [Line Items]
Long-term Debt					40,000,000		40,000,000				40,000,000
Principal Amount | Secured Debt | Senior Secured Term B-3 Loans
Debt Instrument [Line Items]
Long-term Debt					20,000,000		20,000,000				0
Principal Amount | Secured Debt | Senior Secured Multi-Currency Revolver
Debt Instrument [Line Items]
Long-term Debt					18,000,000		18,000,000				90,000,000
Principal Amount | Secured Debt | Senior secured term B-4 loans
Debt Instrument [Line Items]
Long-term Debt					2,119,000,000		2,119,000,000				0
Principal Amount | Secured Debt | Senior Secured Term B-6 Loans
Debt Instrument [Line Items]
Long-term Debt					537,000,000		537,000,000				1,128,000,000
Principal Amount | Secured Debt | 9% Senior secured notes
Debt Instrument [Line Items]
Long-term Debt					290,000,000		290,000,000				290,000,000
Principal Amount | Secured Debt | Senior secured notes
Debt Instrument [Line Items]
Long-term Debt					1,009,000,000		1,009,000,000				1,009,000,000
Principal Amount | Secured Debt | 10.50% Senior secured notes
Debt Instrument [Line Items]
Long-term Debt					1,384,000,000		1,384,000,000				1,384,000,000
Net of Discounts and Issuance Costs
Debt Instrument [Line Items]
Long-term Debt					5,954,000,000		5,954,000,000				5,968,000,000
Net of Discounts and Issuance Costs | Secured Debt | Senior Secured Multi-Currency Asset-Based Revolver
Debt Instrument [Line Items]
Long-term Debt					40,000,000		40,000,000				40,000,000
Net of Discounts and Issuance Costs | Secured Debt | Senior Secured Term B-3 Loans
Debt Instrument [Line Items]
Long-term Debt					20,000,000		20,000,000				0
Net of Discounts and Issuance Costs | Secured Debt | Senior Secured Multi-Currency Revolver
Debt Instrument [Line Items]
Long-term Debt					18,000,000		18,000,000				88,000,000
Net of Discounts and Issuance Costs | Secured Debt | Senior secured term B-4 loans
Debt Instrument [Line Items]
Long-term Debt					2,081,000,000		2,081,000,000				0
Net of Discounts and Issuance Costs | Secured Debt | Senior Secured Term B-6 Loans
Debt Instrument [Line Items]
Long-term Debt					532,000,000		532,000,000				1,113,000,000
Net of Discounts and Issuance Costs | Secured Debt | 9% Senior secured notes
Debt Instrument [Line Items]
Long-term Debt					286,000,000		286,000,000				285,000,000
Net of Discounts and Issuance Costs | Secured Debt | Senior secured notes
Debt Instrument [Line Items]
Long-term Debt					998,000,000		998,000,000				996,000,000
Net of Discounts and Issuance Costs | Secured Debt | 10.50% Senior secured notes
Debt Instrument [Line Items]
Long-term Debt					$ 1,367,000,000		$ 1,367,000,000				$ 1,366,000,000