Property plant and equipment (Details) (USD $) In Thousands, unless otherwise specified	Dec. 28, 2013	Dec. 29, 2012
Property, Plant and Equipment [Line Items]
Cost	$ 273,173	$ 241,024
Accumulated depreciation	115,100	100,445
Net book value	158,073	140,579
Land [Member]
Property, Plant and Equipment [Line Items]
Cost	7,486	7,659
Accumulated depreciation	0	0
Net book value	7,486	7,659
Buildings [Member]
Property, Plant and Equipment [Line Items]
Cost	67,612	59,388
Accumulated depreciation	18,507	15,793
Net book value	49,105	43,595
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	174,454	153,204
Accumulated depreciation	80,505	69,841
Net book value	93,949	83,363
Enterprise Software [Member]
Property, Plant and Equipment [Line Items]
Cost	6,850	7,164
Accumulated depreciation	5,535	5,878
Net book value	1,315	1,286
Office Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	10,041	7,581
Accumulated depreciation	6,033	4,897
Net book value	4,008	2,684
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Cost	6,730	6,028
Accumulated depreciation	4,520	4,036
Net book value	$ 2,210	$ 1,992

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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