Intangible Assets, by Major Class (Details) (USD $)	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 709,190,000	$ 694,450,000
Accumulated Amortization	(263,691,000)	(164,314,000)
Net Amount	445,499,000	530,136,000
Amortization of acquired intangible assets	99,400,000	115,800,000	13,000,000
Impairment of intangible assets	350,000	0	0
Projected Amortization Expense
2015	132,951,000
2016	91,711,000
2017	61,997,000
2018	46,724,000
2019	38,730,000
Cost of sales [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	4,700,000	3,900,000	1,400,000
Operating Expense [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangible assets	94,700,000	111,900,000	11,600,000
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	1 year
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years
Developed Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	402,669,000	375,006,000
Accumulated Amortization	(117,222,000)	(69,107,000)
Net Amount	285,447,000	305,899,000
Acquired Finite-lived Intangible Asset, Amount	12,700,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	11 years
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	195,800,000	194,500,000
Accumulated Amortization	(109,170,000)	(68,522,000)
Net Amount	86,630,000	125,978,000
Acquired Finite-lived Intangible Asset, Amount	1,300,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years
Trademarks and trade names [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	15,730,000	15,730,000
Accumulated Amortization	(7,118,000)	(3,941,000)
Net Amount	8,612,000	11,789,000
Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	24,610,000	24,610,000
Accumulated Amortization	(24,610,000)	(17,310,000)
Net Amount	0	7,300,000
In-process technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	64,396,000	78,968,000
Accumulated Amortization	0	0
Net Amount	64,396,000	78,968,000
Acquired Finite-lived Intangible Asset, Amount	800,000
Distribution rights [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	5,585,000	5,236,000
Accumulated Amortization	(5,171,000)	(5,101,000)
Net Amount	414,000	135,000
Acquired Finite-lived Intangible Asset, Amount	300,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years
Covenants not to compete [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	400,000	400,000
Accumulated Amortization	(400,000)	(333,000)
Net Amount	$ 0	$ 67,000