CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Mar. 31, 2018 USD ($)	Apr. 01, 2017 USD ($)	Apr. 02, 2016 USD ($)
Restructuring Costs and Asset Impairment Charges	$ 5,610	$ 0	$ 0
Proceeds from Divestiture of Businesses	2,999	0	0
Cash, Cash Equivalents, and Restricted Cash; At Carrying Value	77,885	57,732	42,413
CASH FLOWS FROM OPERATING ACTIVITIES
Net (loss) income	116,223	(37,409)	(12,257)
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Depreciation and amortization	7,817	7,566	7,343
Amortization	1,373	1,530	1,376
Share-based compensation expense	4,802	7,095	5,103
Provision for (recovery of) doubtful accounts	731		329
Allowance for Doubtful Accounts Receivable, Recoveries		(429)
Gain on sale of property and equipment, net	197	1,323	862
Business Combination, Bargain Purchase, Gain Recognized, Amount	917	0	0
Impairment of Intangible Assets, Finite-lived	0	2,349	0
Impairment of Inventory due to Restructuring	8,200	1,700	1,400
Inventory Write-down	8,248	2,440	0
Goodwill, Impairment Loss	0	7,445	0
Decrease (increase) in deferred income taxes	(42,251)	(254)	(877)
Changes in operating accounts, net of acquisitions:
Decrease (increase) in trade receivables, net	(22,415)	2,571	2,984
Decrease (increase) in inventories	(37,241)	(6,252)	(7,303)
Decrease (increase) in shipped systems pending acceptance	979	(4,532)	1,631
Decrease (increase) in other current assets	1,249	(755)	1,154
Increase (decrease) in accounts payable and accrued liabilities	27,917	8,141	9,048
Increase (decrease) in deferred revenue	(4,894)	8,338	(4,691)
Net cash (usedin) provided by operating activities	67,428	(833)	4,702
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of investments	(73,044)	(464,893)	(380,841)
Proceeds from sales and maturities of investments	32,666	473,842	369,700
Purchase of property, plant and equipment	(4,848)	(4,039)	(3,693)
Proceeds from sale of property, plant and equipment	37	7	232
Cash paid to acquire subsidiaries	0	2,010	0
Decrease (increase) in other assets	(5,163)	(293)	790
Net cash provided by (used in) investing activities	(47,353)	2,614	(13,812)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from Issuance of Common Stock	3,463	1,398	1,362
Proceeds from Issuance of Other Long-term Debt	0	13,683	0
Repayments of Long-term Debt	(434)	(77)	0
Payments Related to Tax Withholding for Share-based Compensation	(4,161)	(839)	(638)
Stock Repurchased During Period, Value	0	0	0
Net cash (used in) provided by financing activities	(1,132)	14,165	724
Effect of exchange rate changes on cash	1,210	(627)	(195)
CashAndCashEquivalentsAndRestrictedCashPeriodIncreaseDecrease	20,153	15,319	(8,581)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	56,642
CASH AND CASH EQUIVALENTS AT END OF PERIOD	76,792	56,642
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for interest	(652)	(121)	(57)
Cash paid for income taxes	(1,198)	(530)	(806)
Income tax refunds received	132	123	140
Property, Plant and Equipment, Gross, Period Increase (Decrease)	(1,039)	5,985	3,866
Property, Plant and Equipment, Additions	$ 1,899	$ 40	766
Retained Earnings [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net (loss) income			$ (12,257)