Income Taxes (Narratives) (Details) - USD ($)		3 Months Ended		6 Months Ended
	Dec. 22, 2017	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Provision (benefit) for income taxes		$ (1,617,000)	$ 1,179,000		$ 58,000	$ 2,086,000
U.S. Federal tax rate					35.00%
Tax provision offset by tax benefit		2,500,000			$ 2,500,000
Description of effective date of enacted tax rate implementation					Effective for tax years beginning on or after January 1, 2018.
Tax benefit		2,500,000
Additional tax provision resulting corresponding reduction in valuation allowance		0			$ 0
Unrecognized tax benefits		19,000,000			19,000,000
Unrecognized tax benefit future impact if recognized		18,900,000			18,900,000
Enterasys, Zebra WLAN Business and Campus Fabric Business
Operating Loss Carryforwards [Line Items]
Tax amortization deduction for capitalized goodwill		2,100,000	$ 3,700,000		2,100,000	$ 3,700,000
Deferred tax liability, goodwill		$ 4,900,000			$ 4,900,000
Amortization period for tax purposes					15 years
Fiscal 2018
Operating Loss Carryforwards [Line Items]
U.S. Federal tax rate	28.00%
Scenario, Forecast
Operating Loss Carryforwards [Line Items]
U.S. Federal tax rate				21.00%