Balance Sheet Accounts (Narratives) (Details) - USD ($)		3 Months Ended
	Jul. 14, 2017	Sep. 30, 2017	Oct. 26, 2016
Balance Sheet Accounts [Line Items]
Additional goodwill related to acquisition		$ 38,338,000
Borrowings under Term Loan		$ 80,000,000
Standard hardware warranty period (in months)		12 months
Standard software warranty period (in days)		90 days
Limited lifetime hardware warranty maximum period after end of sale of product (in years)		5 years
Maximum investment in one obligor or maker (percent)		10.00%
Accounts Receivable | Jenne Corporation
Balance Sheet Accounts [Line Items]
Concentration risk (percent)		17.00%
Accounts Receivable | Westcon Group Inc.
Balance Sheet Accounts [Line Items]
Concentration risk (percent)		15.00%
Accounts Receivable | Tech Data Corporation
Balance Sheet Accounts [Line Items]
Concentration risk (percent)		13.00%
Term Loan
Balance Sheet Accounts [Line Items]
Interest rate, floor		0.00%
Term Loan | London Interbank Offered Rate (LIBOR)
Balance Sheet Accounts [Line Items]
Interest rate, applicable margin		3.25%
Term Loan | Adjusted Base Rate
Balance Sheet Accounts [Line Items]
Interest rate, applicable margin		1.25%
Revolving Facility
Balance Sheet Accounts [Line Items]
Interest rate, floor		0.00%
Borrowings available under facility		$ 49,100,000
Outstanding letters of credit		$ 900,000
Revolving Facility | London Interbank Offered Rate (LIBOR)
Balance Sheet Accounts [Line Items]
Interest rate, applicable margin		3.25%
Revolving Facility | Adjusted Base Rate
Balance Sheet Accounts [Line Items]
Interest rate, applicable margin		1.25%
Avaya Networking
Balance Sheet Accounts [Line Items]
Additional goodwill related to acquisition		$ 38,300,000
Borrowings under Term Loan	$ 80,000,000
Avaya Networking | Credit Facility
Balance Sheet Accounts [Line Items]
Borrowing capacity from Credit Agreement			$ 140,500,000
Avaya Networking | Second Amendment | Credit Facility
Balance Sheet Accounts [Line Items]
Borrowing capacity from Credit Agreement	243,700,000
Avaya Networking | Second Amendment | Term Loan
Balance Sheet Accounts [Line Items]
Borrowing capacity from Credit Agreement	$ 183,700,000
Credit Facility, as amended term	5 years
Avaya Networking | Second Amendment | Revolving Facility
Balance Sheet Accounts [Line Items]
Borrowing capacity from Credit Agreement	$ 60,000,000
Credit Facility, as amended term	5 years
Developed technology | In-process research and development, with indefinite life
Balance Sheet Accounts [Line Items]
In-process research and development reclassified to developed technology		$ 1,400,000
Maximum
Balance Sheet Accounts [Line Items]
Extended warranty period		5 years
Maximum | Revolving Facility
Balance Sheet Accounts [Line Items]
Commitment fee		0.50%
Maximum | Avaya Networking | Second Amendment
Balance Sheet Accounts [Line Items]
Additional incremental loan facility	$ 50,000,000
Minimum
Balance Sheet Accounts [Line Items]
Extended warranty period		1 year
Minimum | Revolving Facility
Balance Sheet Accounts [Line Items]
Commitment fee		0.375%
Cash equivalents | Maximum
Balance Sheet Accounts [Line Items]
Maturity period for investments		3 months
Short-term investments | Maximum
Balance Sheet Accounts [Line Items]
Maturity period for investments		1 year
Short-term investments | Minimum
Balance Sheet Accounts [Line Items]
Maturity period for investments		3 months