Intangible Assets, by Major Class (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Aug. 03, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2015
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		$ 1,227,631		$ 1,227,631		$ 949,067
Accumulated Amortization		(525,248)		(525,248)		(444,650)
Net Amount		702,383		702,383		504,417
In-process technology reaching technological feasibility and reclassified				28,300
Amortization of Intangible Assets		44,900	$ 46,500	80,600	$ 84,200
Impairment of Intangible Assets		530	200	530	556
Projected Amortization Expense
Future Amortization Expense, Remainder of Fiscal Year		98,775		98,775
Future Amortization Expense, Year Two		137,051		137,051
Future Amortization Expense, Year Three		110,462		110,462
Future Amortization Expense, Year Four		93,561		93,561
Future Amortization Expense, Year Five		75,320		75,320
Core and developed technology [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		778,835		778,835		569,942
Accumulated Amortization		(258,503)		(258,503)		(209,676)
Net Amount		$ 520,332		520,332		360,266
Useful Life		10 years
Minimum expected useful life of finite lived intangible assets (in years)		10 years
Customer-related [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		$ 334,369		334,369		263,969
Accumulated Amortization		(222,817)		(222,817)		(193,483)
Net Amount		$ 111,552		111,552		70,486
Useful Life		5 years
Minimum expected useful life of finite lived intangible assets (in years)		5 years
Trademarks and trade names [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		$ 15,730		15,730		15,730
Accumulated Amortization		(10,569)		(10,569)		(9,529)
Net Amount		5,161		5,161		6,201
Backlog [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		31,804		31,804		26,304
Accumulated Amortization		(27,679)		(27,679)		(26,304)
Net Amount		$ 4,125		4,125		0
Useful Life		1 year
Minimum expected useful life of finite lived intangible assets (in years)		1 year
In-process technology [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		$ 60,914		60,914		67,142
Accumulated Amortization		0		0		0
Net Amount		60,914		60,914		67,142
Distribution rights [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		5,579		5,579		5,580
Accumulated Amortization		(5,280)		(5,280)		(5,258)
Net Amount		299		299		322
Covenants not to compete [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		400		400		400
Accumulated Amortization		(400)		(400)		(400)
Net Amount		0		$ 0		$ 0
Minimum [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Useful Life				1 year
Minimum expected useful life of finite lived intangible assets (in years)				1 year
Maximum [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Useful Life				15 years
Minimum expected useful life of finite lived intangible assets (in years)				15 years
Micrel Incorporated [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Purchased Intangible Assets	$ 274,800
Micrel Incorporated [Member] | Core and developed technology [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Purchased Intangible Assets	$ 176,800	176,800
Useful Life	10 years
Minimum expected useful life of finite lived intangible assets (in years)	10 years
Micrel Incorporated [Member] | Customer-related [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Purchased Intangible Assets	$ 70,400	70,400
Useful Life	5 years
Minimum expected useful life of finite lived intangible assets (in years)	5 years
Micrel Incorporated [Member] | Backlog [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Purchased Intangible Assets	$ 5,500	5,500
Useful Life	1 year
Minimum expected useful life of finite lived intangible assets (in years)	1 year
Micrel Incorporated [Member] | In-process technology [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Purchased Intangible Assets	$ 22,100	22,100
Useful Life	10 years
Minimum expected useful life of finite lived intangible assets (in years)	10 years
Cost of Sales [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Amortization of Intangible Assets		900	1,000	$ 1,700	2,000
Operating Expense [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Amortization of Intangible Assets		$ 44,000	$ 45,500	$ 78,900	$ 82,200