Supplemental cash flow information (Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Increase (Decrease) in Receivables	$ (3,059)	$ 35,773	$ (39,857)
Increase (Decrease) in Inventories	(16,032)	27,475	(16,107)
Increase (Decrease) in Accrued Taxes Payable	5,744	(13,515)	22,868
Increase (Decrease) in Prepaid Expense and Other Assets	3,662	(11,994)	(242)
Increase (Decrease) in Accounts Payable and Accrued Liabilities	(6,225)	(20,437)	23,221
Increase (Decrease) in Deferred Revenue and Customer Advances and Deposits	(3,457)	2,328	(2,774)
Increase (Decrease) In Operating Capital	(19,367)	19,630	(12,891)
Interest Paid	32,020	29,683	28,651
Income Taxes Paid, Net	$ 2,936	$ 4,150	$ 1,781

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4297-108586

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The increase (decrease) during the reporting period in the amounts payable to vendors for goods and services received and the amount of obligations and expenses incurred but not paid.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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The increase (decrease) during the reporting period of all taxes owed but not paid, including income, property and other taxes.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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The increase (decrease) during the reporting period in the amount of (a) prepayments by customers for goods or services to be provided at a later date, (b) the amount of customer money held in customer accounts, including security deposits, collateral for current or future transactions, initial payment of the cost of an acquisition or for the right to enter into a contract or agreement, (c) the increase (decrease) during the reporting period, excluding the portion taken into income, in the liability reflecting services yet to be performed by the reporting entity for which cash or other forms of consideration was received or recorded as a receivable, or (d) some combination of (a), (b), and (c).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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- Definition

The increase (decrease) during the reporting period in the aggregate value of all inventory held by the reporting entity, associated with underlying transactions that are classified as operating activities.

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The increase (decrease) during the reporting period of all assets and liabilities used in operating activities.

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Amount of increase (decrease) in prepaid expenses, and assets classified as other.

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The increase (decrease) during the reporting period in the total amount due within one year (or one operating cycle) from all parties, associated with underlying transactions that are classified as operating activities.

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Amount of cash paid for interest, including, but not limited to, capitalized interest and payment to settle zero-coupon bond attributable to accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount; classified as operating and investing activities.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 2
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No definition available.

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