Share-Based Compensation (Details) - USD ($) $ in Thousands			3 Months Ended			6 Months Ended
		Apr. 04, 2016	Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015
Stock-based compensation expense [Line Items]
Allocated share-based compensation expense			$ 24,390		$ 23,026	$ 83,969		$ 37,138
Income tax benefit			8,358		8,574	29,246		12,106
Net income effect of share-based compensation			16,032		14,452	54,723		25,032
Share-based compensation expense previously capitalized	[1]		4,100
Inventory
Stock-based compensation expense [Line Items]
Amount of share-based compensation expense capitalized to inventory			2,700		1,800	5,500		3,600
Share-based compensation expense previously capitalized	[1]					7,800
Cost of Sales
Stock-based compensation expense [Line Items]
Allocated share-based compensation expense			4,100	[1]	2,398	11,997	[1]	4,055	[1]
Research and development
Stock-based compensation expense [Line Items]
Allocated share-based compensation expense			10,171		8,670	27,688		15,768
Selling, General and Administrative
Stock-based compensation expense [Line Items]
Allocated share-based compensation expense			10,119		$ 11,958	44,284		$ 17,315
Atmel Corporation
Stock-based compensation expense [Line Items]
Allocated share-based compensation expense	[1]		$ 6,200			49,400
Share-based compensation expense previously capitalized	[1]					4,200
Business combination fair value of assumed awards at acquisition date		$ 95,900
Non cash consideration of certain share-based payment awards		7,500
Nonvested awards, compensation cost not yet recognized		$ 88,400
Accelerated compensation cost						$ 37,200

[1] During the three and six months ended September 30, 2016, $2.7 million and $5.5 million, respectively, of share-based compensation expense was capitalized to inventory. The amount of share-based compensation included in cost of sales during the three months ended September 30, 2016 included $4.1 million of previously capitalized share-based compensation expense in inventory that was sold. The amount of share-based compensation included in cost of sales during the six months ended September 30, 2016 included $7.8 million of previously capitalized share-based compensation expense in inventory that was sold and $4.2 million of share-based compensation expense related to the Company's acquisition of Atmel that was not previously capitalized to inventory. During the three and six months ended September 30, 2015, $1.8 million and $3.6 million, respectively, of share-based compensation expense was capitalized to inventory and $2.4 million and $4.1 million, respectively, of previously capitalized share-based compensation expense in inventory was sold.