Goodwill Impairment Test, Sensitivity Analysis, Decrease of Operating Margin

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Goodwill Impairment Test, Sensitivity Analysis, Decrease of Projected Revenue Growth

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Goodwill Impairment Test, Sensitivity Analysis, Decrease of Selling Margin

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Goodwill Impairment Test, Sensitivity Analysis, Increase of Weighted-Average Cost of Capital

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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GOODWILL AND INTANGIBLE ASSETS - Narrative (Details) $ in Thousands	12 Months Ended
	Mar. 31, 2016 USD ($) Segment	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Number of operating segments \| Segment	5
Goodwill	$ 1,709,369	$ 197,445	$ 203,446
Carrying value of intangible assets	1,054,040	50,180
Amortization expenses	$ 32,373	3,351	3,432
Weighted average useful life of acquired intangible assets	14 years 7 months 2 days
Technology license
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 3,700
Weighted average useful life of acquired intangible assets	4 years
Acquired software and core technology \| Included as cost of product revenue
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expenses	$ 45,100	3,600	3,300
Other acquired intangible assets \| Included as operating expense
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expenses	$ 32,500	3,500	$ 3,600
Developed and core technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	11 years 6 months
Customer and distributor relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	16 years 1 month 18 days
Trademarks and trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	8 years 6 months
Leasehold interest
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	5 years 7 months
Backlog
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	2 years
Capitalized software
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life of acquired intangible assets	4 years
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 18,600	18,600
Legacy
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	198,100	$ 197,400
Arbor Networks
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 534,800
Goodwill impairment test, sensitivity analysis, decrease of projected revenue growth	3.00%
Goodwill impairment test, sensitivity analysis, decrease of selling margin	2.00%
Goodwill impairment test, sensitivity analysis,, decrease of operating margin	2.00%
Goodwill impairment test, sensitivity analysis, increase of WACC	75.00%
Tektronix Communications
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 794,400
Goodwill impairment test, sensitivity analysis, decrease of projected revenue growth	3.00%
Goodwill impairment test, sensitivity analysis, decrease of selling margin	4.00%
Goodwill impairment test, sensitivity analysis,, decrease of operating margin	4.00%
Goodwill impairment test, sensitivity analysis, increase of WACC	100.00%
VSS
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 57,000
Goodwill impairment test, sensitivity analysis, decrease of projected revenue growth	17.00%
Goodwill impairment test, sensitivity analysis, decrease of selling margin	8.00%
Goodwill impairment test, sensitivity analysis,, decrease of operating margin	8.00%
Goodwill impairment test, sensitivity analysis, increase of WACC	600.00%
FNET
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 125,100
Goodwill impairment test, sensitivity analysis, decrease of projected revenue growth	16.00%
Goodwill impairment test, sensitivity analysis, decrease of selling margin	7.00%
Goodwill impairment test, sensitivity analysis,, decrease of operating margin	7.00%
Goodwill impairment test, sensitivity analysis, increase of WACC	500.00%