Consolidated Condensed Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Jun. 29, 2019	Jun. 30, 2018
Income Statement [Abstract]
Net sales	$ 238,253	$ 254,483
Cost of sales	115,759	129,924
Gross profit	122,494	124,559
Operating expenses
Research and development	88,830	97,932
Selling, general and administrative	29,520	32,784
Total operating expenses	118,350	130,716
Income (loss) from operations	4,144	(6,157)
Interest income	2,544	1,706
Interest expense	(259)	(259)
Other income (expense)	(378)	210
Income (loss) before income taxes	6,051	(4,500)
Provision (benefit) for income taxes	1,433	(228)
Net income (loss)	$ 4,618	$ (4,272)
Basic earnings (loss) per share (in dollars per share)	$ 0.08	$ (0.07)
Diluted earnings (loss) per share (in dollars per share)	$ 0.08	$ (0.07)
Basic weighted average common shares outstanding (in shares)	58,540	61,462
Diluted weighted average common shares outstanding (in shares)	60,258	61,462