Business combinations (Narrative) (Details) (USD $)	9 Months Ended		0 Months Ended			9 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Sep. 30, 2014	Dec. 31, 2013	Oct. 31, 2013	Sep. 30, 2014
Business Acquisition [Line Items]
Purchase price paid in acquisition	$ 0	$ 180,000,000
Enterasys Networks, Inc.
Business Acquisition [Line Items]
Purchase price paid in acquisition			180,000,000	180,000,000	180,000,000
Change during the period, Receivables						2,428,000	[1]
Goodwill, increase (decrease)						2,400,000
Change during the period, other current assets						1,514,000	[2]
Change during the period, Property and equipment						(1,829,000)	[3]
Increase (decrease) in current liabilities for litigation and statutory tax assessments						5,400,000
Increase (decrease) for accrued liabilities						500,000
Enterasys Networks, Inc. | Order backlog
Business Acquisition [Line Items]
Finite-lived intangible asset useful lives			1 year			1 year 6 months
Enterasys Networks, Inc. | Goodwill
Business Acquisition [Line Items]
Change during the period, Property and equipment						3,000,000
Enterasys Networks, Inc. | Property, Plant and Equipment
Business Acquisition [Line Items]
Change during the period, Property and equipment						1,200,000
Enterasys Networks, Inc. | Other Current Liabilities
Business Acquisition [Line Items]
Change during the period, Property and equipment						200,000
Enterasys Networks, Inc. | Other Noncurrent Liabilities
Business Acquisition [Line Items]
Change during the period, Property and equipment						$ 1,000,000

[1] The Company finalized the working capital adjustment as of September 30, 2014, which led to a decrease of $2.4 million in receivables and a corresponding increase in cash. As a result of this adjustment, the total cash acquired from the acquisition also increased by the same amount. The net effect of this adjustment is an increase in goodwill of $2.4 million.

[2] The Company obtained new information regarding the existence of prepaid assets as of the acquisition date which led to a decrease in the fair value of current assets of $1.5 million, and a corresponding increase in goodwill. The change in the amortization of prepaid assets due to the change in fair value of current assets was immaterial.

[3] The Company updated its preliminary estimate of the fair value of property and equipment which led to a decrease of $3.0 million in property and equipment with a corresponding increase in goodwill. The Company also updated the fair values of the asset retirement obligations and the related asset retirement assets which led to an increase in the fair value of property and equipment of $1.2 million and a corresponding increase in current liabilities and other long-term liabilities of $0.2 million and $1.0 million, respectively. The decrease in depreciation expense due to the change in fair value of property and equipment was immaterial.