Note 6. Cash, Cash Equivalents and Short Term Marketable Securities (Detail) - Investment Assets Measured at Fair Value (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Apr. 01, 2012
Assets:
Investment	$ 195,629	$ 190,756
Investment, percentage	100.00%	100.00%
Liabilities:
Acquisition-related contingent consideration	10,138
Acquisition-related contingent consideration	100.00%
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets:
Investment	5,042	3,088
Fair Value, Inputs, Level 1 [Member] | US Government Agencies Debt Securities [Member]
Assets:
Investment	22,460	16,282
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Assets:
Investment	274
Fair Value, Inputs, Level 1 [Member]
Assets:
Investment	27,776	19,370
Fair Value, Inputs, Level 2 [Member] | US Government Agencies Debt Securities [Member]
Assets:
Investment	19,261	27,954
Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Assets:
Investment	2,935	590
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Assets:
Investment	91,955	69,234
Fair Value, Inputs, Level 2 [Member] | Asset-backed Securities [Member]
Assets:
Investment	30,966	26,364
Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage Backed Securities [Member]
Assets:
Investment	22,736	47,244
Fair Value, Inputs, Level 2 [Member]
Assets:
Investment	167,853	171,386
Fair Value, Inputs, Level 3 [Member]
Liabilities:
Acquisition-related contingent consideration	10,138
Money Market Funds [Member]
Assets:
Investment	5,042	3,088
Investment, percentage	3.00%	2.00%
US Government Agencies Debt Securities [Member]
Assets:
Investment	41,721	44,236
Investment, percentage	21.00%	23.00%
US States and Political Subdivisions Debt Securities [Member]
Assets:
Investment	2,935	590
Investment, percentage	1.00%
Corporate Debt Securities [Member]
Assets:
Investment	92,229	69,234
Investment, percentage	47.00%	36.00%
Asset-backed Securities [Member]
Assets:
Investment	30,966	26,364
Investment, percentage	16.00%	14.00%
Collateralized Mortgage Backed Securities [Member]
Assets:
Investment	$ 22,736	$ 47,244
Investment, percentage	12.00%	25.00%