The total of contractually required rental payments on leases meeting the criteria for capitalization.

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Contractually required rental payments on leases meeting the criteria for capitalization, due within one year of the balance sheet date.

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Contractually required rental payments on leases meeting the criteria for capitalization, due within the fifth year from the balance sheet date.

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Rental expense incurred for leased assets including furniture and equipment which has not been recognized in costs and expenses applicable to sales and revenues; for example, cost of goods sold or other operating costs and expenses.

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The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings.

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Commitments and contingencies (Details) (USD $)	12 Months Ended
Commitments and contingencies (Details) (USD $)	Dec. 30, 2011	Dec. 31, 2010	Dec. 25, 2009
Aggregate minimum rental commitments under non-cancelable leases [Abstract]
2012	$ 4,435,000
2013	2,087,000
2014	1,512,000
2015	1,242,000
2016	857,000
Thereafter	1,672,000
Total rent expense	11,805,000
Rental expense	6,300,000	6,900,000	7,300,000
Pending or Threatened Litigation Halo [Member]
Loss Contingencies [Line Items]
Value of damages sought by plaintiff	34,300,000
Selling, general and administrative charges related to Halo	200,000
Legal expenses	800,000	2,500,000
Unsolicited Takeover Attempt Bel Fuse, Inc. [Member]
Loss Contingencies [Line Items]
Legal expenses	$ 1,900,000