Share-Based Compensation (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
Stock-based compensation expense [Line Items]
Allocated share-based compensation expense			$ 24,003	$ 22,120	$ 70,021	$ 106,089
Income tax benefit			6,604	7,376	21,878	36,622
Net income effect of share-based compensation			17,399	14,744	48,143	69,467
Share-based compensation expense previously capitalized			3,500		10,600
Inventory
Stock-based compensation expense [Line Items]
Income tax benefit			3,100	2,800	8,900	8,300
Share-based compensation expense previously capitalized				3,500		11,300
Cost of Sales
Stock-based compensation expense [Line Items]
Allocated share-based compensation expense			3,494	3,468	10,587	15,465
Research and development
Stock-based compensation expense [Line Items]
Allocated share-based compensation expense			10,921	9,881	31,797	37,569
Selling, General and Administrative
Stock-based compensation expense [Line Items]
Allocated share-based compensation expense			9,588	8,771	27,637	53,055
Atmel Corporation
Stock-based compensation expense [Line Items]
Allocated share-based compensation expense	[1]		3,900		53,300
Share-based compensation expense previously capitalized						4,200
Non cash consideration of certain share-based payment awards		$ 7,500
Accelerated compensation cost					38,800
New Accounting Pronouncement, Early Adoption, Effect | Accounting Standards Update 2016-09, Excess Tax Benefit Component
Stock-based compensation expense [Line Items]
Allocated share-based compensation expense			$ 5,700	$ 6,100	$ 19,800	$ 18,600

[1] During the three and nine months ended December 31, 2017, $3.1 million and $8.9 million, respectively, of share-based compensation expense was capitalized to inventory and $3.5 million and $10.6 million, respectively, of previously capitalized share-based compensation expense in inventory was sold. During the three and nine months ended December 31, 2016, $2.8 million and $8.3 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 December 31, 2016 included $3.5 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 nine months ended December 31, 2016 included $11.3 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.