Selected Financial Statement Data - Property and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Apr. 27, 2013	Apr. 28, 2012
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 195,266	$ 192,327
Less accumulated depreciation	133,641	123,931
Property and equipment, net	61,625	68,396
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,497	1,497
Buildings
Property, Plant and Equipment [Line Items]
Property and equipment, gross	57,012	56,431
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	65,600	61,654
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	16,118	15,648
Computer software and hardware
Property, Plant and Equipment [Line Items]
Property and equipment, gross	41,745	42,172
Equipment held for rental
Property, Plant and Equipment [Line Items]
Property and equipment, gross	868	1,003
Demonstration equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	8,400	9,806
Transportation equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 4,026	$ 4,116

The cumulative amount of depreciation, depletion and amortization (related to property, plant and equipment, but not including land) that has been recognized in the income statement.

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Gross amount of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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- Definition

Amount, net of accumulated depreciation, depletion and amortization, of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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