Mergers and Acquisitions (Details) - USD ($) $ in Millions						3 Months Ended								12 Months Ended
	Jan. 27, 2014	Jan. 06, 2014	Dec. 10, 2013	Mar. 07, 2013	Aug. 17, 2012	Jun. 27, 2015	Mar. 28, 2015	Dec. 27, 2014	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 28, 2013	Sep. 28, 2013	Jun. 27, 2015	Jun. 28, 2014	Jun. 29, 2013
Purchase price allocation to assets acquired
Goodwill.						$ 261.1				$ 267.0				$ 261.1	$ 267.0	$ 115.1
Additional business acquisition information
Net revenue						427.7	$ 410.7	$ 437.1	$ 433.6	448.6	$ 418.0	$ 447.6	$ 429.0	1,709.1	1,743.2	1,676.9
Net (loss) income						(40.1)	$ (13.2)	$ (25.1)	$ (9.7)	(25.4)	$ (1.5)	$ 8.8	$ 0.3	(88.1)	(17.8)	57.0
Network Instruments, LLC ("Network Instruments")
Acquisitions
Purchase price paid in cash		$ 208.5
Working capital adjustment and holdback payment		20.0
Holdback payment						19.7								19.7
Purchase price allocation to assets acquired
Net tangible assets acquired		20.8
Goodwill.		125.6
Total purchase price		208.4
Fair value of acquired tangible assets
Cash		9.0
Accounts receivable		13.8
Inventories		6.0
Property and equipment		1.0
Accounts payable		(1.5)
Deferred tax liabilities, net		(0.6)
Other liabilities, net of other assets		(4.4)
Deferred revenue		(2.5)
Net tangible assets acquired		20.8
Additional business acquisition information
Net revenue															12.6
Net (loss) income															(9.6)
Pro forma information in pursuant with acquisition
Pro forma net revenue															1,770.0	1,710.9
Pro forma net (loss) income															(14.5)	47.7
Network Instruments, LLC ("Network Instruments") | In-process research and development
Purchase price allocation to assets acquired
Intangible assets acquired		1.7
Network Instruments, LLC ("Network Instruments") | Developed technology
Purchase price allocation to assets acquired
Intangible assets acquired		$ 21.7
Additional business acquisition information
Estimated useful lives of intangible assets		5 years
Network Instruments, LLC ("Network Instruments") | Customer relationships
Purchase price allocation to assets acquired
Intangible assets acquired		$ 38.3
Additional business acquisition information
Estimated useful lives of intangible assets		5 years
Network Instruments, LLC ("Network Instruments") | Tradename
Additional business acquisition information
Estimated useful lives of intangible assets		1 year
Network Instruments, LLC ("Network Instruments") | Other
Purchase price allocation to assets acquired
Intangible assets acquired		$ 0.3
Time-Bandwidth Products AG ("Time-Bandwidth")
Acquisitions
Purchase price paid in cash	$ 15.0
Working capital adjustment and holdback payment	$ 2.3
Minimum period after which the holdback payments will be released	18 months
Purchase price allocation to assets acquired
Net tangible assets acquired	$ 2.0
Goodwill.	5.8
Total purchase price	15.0
Fair value of acquired tangible assets
Accounts receivable	1.4
Inventories	5.0
Property and equipment	1.5
Accounts payable	(0.6)
Accrued expenses, net of other assets	(3.5)
Deferred tax liabilities, net	(1.8)
Net tangible assets acquired	2.0
Time-Bandwidth Products AG ("Time-Bandwidth") | Developed technology
Purchase price allocation to assets acquired
Intangible assets acquired	$ 6.7
Additional business acquisition information
Estimated useful lives of intangible assets	8 years
Time-Bandwidth Products AG ("Time-Bandwidth") | Customer relationships
Purchase price allocation to assets acquired
Intangible assets acquired	$ 0.5
Additional business acquisition information
Estimated useful lives of intangible assets	3 years
Trendium Inc. ("Trendium")
Acquisitions
Purchase price paid in cash			$ 26.1
Working capital adjustment and holdback payment			$ 2.5
Minimum period after which the holdback payments will be released			1 year
Holdback payment						$ 2.5								$ 2.5
Purchase price allocation to assets acquired
Goodwill.			$ 14.4
Total purchase price			26.1
Fair value of acquired tangible assets
Property and equipment			0.2
Trendium Inc. ("Trendium") | In-process research and development
Purchase price allocation to assets acquired
Intangible assets acquired			5.4
Trendium Inc. ("Trendium") | Developed technology
Purchase price allocation to assets acquired
Intangible assets acquired			$ 6.1
Additional business acquisition information
Estimated useful lives of intangible assets			7 years
Arieso Ltd. ("Arieso")
Acquisitions
Purchase price paid in cash				$ 89.7
Working capital adjustment and holdback payment				12.8
Holdback payment										7.0					7.0
Purchase price allocation to assets acquired
Net tangible assets acquired				0.2
Goodwill.				40.8
Total purchase price				89.7
Fair value of acquired tangible assets
Cash				4.1
Accounts receivable				8.4
Property and equipment				0.6
Accounts payable				(0.3)
Accrued expenses, net of other assets				(1.4)
Employee related liabilities				(1.4)
Deferred tax liabilities, net				(8.1)
Deferred revenue				(1.7)
Net tangible assets acquired				0.2
Additional business acquisition information
Acquisition-related costs																$ 1.8
Arieso Ltd. ("Arieso") | Developed technology
Purchase price allocation to assets acquired
Intangible assets acquired				$ 32.8
Additional business acquisition information
Estimated useful lives of intangible assets				5 years
Arieso Ltd. ("Arieso") | Customer relationships
Purchase price allocation to assets acquired
Intangible assets acquired				$ 14.5
Additional business acquisition information
Estimated useful lives of intangible assets				5 years
Arieso Ltd. ("Arieso") | Order backlog
Purchase price allocation to assets acquired
Intangible assets acquired				$ 1.4
GenComm Co., Ltd. ("GenComm")
Acquisitions
Purchase price paid in cash					$ 15.2
Working capital adjustment and holdback payment					3.8
Holdback payment										$ 3.3					$ 3.3
Purchase price allocation to assets acquired
Net tangible assets acquired					5.9
Goodwill.					5.7
Total purchase price					15.2
Fair value of acquired tangible assets
Net tangible assets acquired					5.9
GenComm Co., Ltd. ("GenComm") | Developed technology
Purchase price allocation to assets acquired
Intangible assets acquired					$ 3.2
Additional business acquisition information
Estimated useful lives of intangible assets					4 years
GenComm Co., Ltd. ("GenComm") | Customer relationships
Purchase price allocation to assets acquired
Intangible assets acquired					$ 0.2
Additional business acquisition information
Estimated useful lives of intangible assets					4 years
GenComm Co., Ltd. ("GenComm") | Order backlog
Purchase price allocation to assets acquired
Intangible assets acquired					$ 0.2