Balance Sheet Accounts (Narratives) (Details) (USD $)	3 Months Ended			6 Months Ended	9 Months Ended					0 Months Ended			3 Months Ended	0 Months Ended	3 Months Ended		9 Months Ended		0 Months Ended			9 Months Ended		0 Months Ended	9 Months Ended	0 Months Ended	9 Months Ended				1 Months Ended
	Mar. 31, 2014 Investment_Securities	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014 Investment_Securities	Mar. 31, 2013	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Oct. 31, 2013 Senior Secured Credit Facilities	Oct. 31, 2013 Senior Secured Credit Facilities Federal Funds Effective Rate	Oct. 31, 2013 Revolving Facility	Mar. 31, 2014 Revolving Facility	Oct. 31, 2013 Term Loan	Mar. 31, 2014 Cost of Product Revenue	Mar. 31, 2013 Cost of Product Revenue	Mar. 31, 2014 Cost of Product Revenue	Mar. 31, 2013 Cost of Product Revenue	Oct. 31, 2013 Enterasys Networks, Inc.	Oct. 31, 2013 Enterasys Networks, Inc. Revolving Facility	Sep. 11, 2012 Santa Clara Headquarters acre	Mar. 31, 2014 Minimum	Mar. 31, 2014 Minimum Net Revenue Customer Concentration Risk	Oct. 31, 2013 Minimum Senior Secured Credit Facilities	Mar. 31, 2014 Maximum	Oct. 31, 2013 Maximum Senior Secured Credit Facilities	Mar. 31, 2014 Cash equivalents Maximum	Mar. 31, 2014 Short-term Investments Minimum	Mar. 31, 2014 Short-term Investments Maximum	Mar. 31, 2014 Marketable Securities Minimum	May 07, 2014 Subsequent Event Revolving Facility
Balance Sheet Accounts [Line Items]
Maturity period for investments																											3 months	3 months	1 year	1 year
Number of securities with unrealized losses	5				5
Number of investment securities	20				20
Other than temporary impairment loss on investments	$ 10,000			$ 148,000	$ 158,000	$ 0
Number of acres of land sold																					16
Net cash proceeds from sale of real estate					0	42,659,000															44,700,000
Gain on sale of property	0		0		0	11,539,000															11,500,000
Addition due to acquisition of Enterasys (Note 4)		57,922,000																	64,500,000
Amortization expense	11,900,000		400,000		18,937,000	1,168,000									4,400,000	300,000	7,300,000	1,000,000
Extended warranty period																						1 year			5 years
Borrowing capacity												60,000,000		65,000,000
Term of agreement												5 years		5 years
Borrowings under Revolving Facility					59,000,000	0							24,000,000							35,000,000
Repayment of draw																															24,000,000
Basis spread											0.50%
Commitment fee percentage										0.50%														0.375%		0.50%
Warranty liability	$ 7,825,000	$ 7,479,000	$ 2,896,000	$ 7,479,000	$ 7,825,000	$ 2,896,000	$ 3,296,000	$ 2,971,000	$ 2,871,000
Standard hardware warranty period					12 months
Standard software warranty period					90 days
Limited lifetime hardware warranty maximum period after end of sale of product					5 years
Maximum investment in one obligor or maker (percent)					10.00%
Concentration risk																							10.00%