Intangible Assets, by Major Class (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Apr. 04, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2017
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		$ 2,702,007		$ 2,702,007		$ 2,706,512
Accumulated Amortization		(917,439)		(917,439)		(558,420)
Net Amount		1,784,568		1,784,568		2,148,092
In-process technology reaching technological feasibility and reclassified				8,900
Amortization of Intangible Assets		122,600	$ 85,200	368,100	$ 250,600
Impairment of Intangible Assets			8,200	252	10,226
Projected Amortization Expense
2018		122,252		122,252
2019		361,682		361,682
2020		313,484		313,484
2021		257,430		257,430
2022		190,429		190,429
Core and developed technology
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		1,936,956		1,936,956		1,932,329
Accumulated Amortization		(587,415)		(587,415)		(419,468)
Net Amount		1,349,541		1,349,541		1,512,861
Customer-related
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		716,945		716,945		716,945
Accumulated Amortization		(312,851)		(312,851)		(123,616)
Net Amount		404,094		404,094		593,329
Trademarks and trade names
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		11,700		11,700		11,700
Accumulated Amortization		(11,185)		(11,185)		(9,636)
Net Amount		515		515		2,064
In-process technology
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		29,379		29,379		38,511
Accumulated Amortization		0		0		0
Net Amount		29,379		29,379		38,511
Distribution rights
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		5,578		5,578		5,578
Accumulated Amortization		(5,379)		(5,379)		(5,346)
Net Amount		199		199		232
Other
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount		1,449		1,449		1,449
Accumulated Amortization		(609)		(609)		(354)
Net Amount		840		$ 840		$ 1,095
Minimum
Finite-Lived Intangible Assets, Net [Abstract]
Useful life				1 year
Maximum
Finite-Lived Intangible Assets, Net [Abstract]
Useful life				15 years
Atmel Corporation
Finite-Lived Intangible Assets, Net [Abstract]
Useful life	9 years
Purchased intangible assets	$ 1,888,392
Atmel Corporation | Core and developed technology
Finite-Lived Intangible Assets, Net [Abstract]
Useful life	11 years
Purchased intangible assets	$ 1,074,987
Atmel Corporation | Other
Finite-Lived Intangible Assets, Net [Abstract]
Useful life	5 years
Purchased intangible assets	$ 1,805
Cost of Sales
Finite-Lived Intangible Assets, Net [Abstract]
Amortization of Intangible Assets		1,500	900	$ 4,900	2,800
Operating Expense
Finite-Lived Intangible Assets, Net [Abstract]
Amortization of Intangible Assets		$ 121,100	$ 84,300	$ 363,200	$ 247,800