CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Dec. 29, 2012	Dec. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 11,035	$ 12,569
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	6,867	8,130
Amortization of acquired intangible assets	1,810	1,307
Share-based compensation expense	6,132	9,546
Provision for doubtful accounts		50
(Gain) loss on sale of property and equipment, net	(1,226)	2
Gain on sale of previously impaired auction rate securities		(2,729)
Deferred income taxes	4,537	(2,109)
Changes in operating accounts:
Decrease in trade receivables, net	14,315	18,502
Increase in inventories	(11,744)	(6,432)
Decrease in shipped systems pending acceptance	1,002	4,050
Decrease in other current assets	61	2,937
Decrease in accounts payable and accrued liabilities	(912)	(21,219)
Decrease in deferred revenue	(4,343)	(7,660)
Net cash provided by operating activities	27,534	16,944
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of investments	(857,435)	(720,961)
Proceeds from sales and maturities of investments	885,818	660,707
Proceeds from sale of auction rate securities		6,450
Increase in restricted cash		(11,500)
Purchase of property, plant and equipment	(5,127)	(4,198)
Proceeds from the sale of property, plant and equipment	2,020
Cash paid for acquisition of Eolite Systems, net of cash acquired	(9,466)
Decrease in other assets	403	174
Net cash provided by (used in) investing activities	16,213	(69,328)
CASH FLOWS FROM FINANCING ACTIVITIES
Cash dividends paid to shareholders	(65,723)
Stock plan activity, net	73	2,345
Excess tax benefit of share-based compensation	71	519
Net cash (used in) provided by financing activities	(65,579)	2,864
Effect of exchange rate changes on cash	(708)	665
NET CHANGE IN CASH AND CASH EQUIVALENTS	(22,540)	(48,855)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	69,780	116,412
CASH AND CASH EQUIVALENTS AT END OF PERIOD	47,240	67,557
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for income taxes	(1,174)	(4,268)
Income tax refunds received	651	132
Dividends declared but not paid		$ 2,311