GOODWILL AND INTANGIBLE ASSETS - Amortized Intangible Assets - (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 30, 2019	Mar. 31, 2018	Dec. 29, 2018
Components of amortized intangible assets
Gross Carrying Amount	$ 272,100		$ 251,141
Accumulated Amortization	149,080		143,908
Amortization expense for intangible assets	4,390	$ 3,883
Estimated amortization expense
2019	18,238
2020	17,404
2021	15,378
2022	13,228
2023	11,483
Customer Relationships
Components of amortized intangible assets
Gross Carrying Amount	240,786		219,508
Accumulated Amortization	$ 136,961		$ 132,180
Weighted Average Life	13 years		13 years
Patents & Proprietary Technology
Components of amortized intangible assets
Gross Carrying Amount	$ 23,396		$ 23,662
Accumulated Amortization	$ 5,232		$ 4,837
Weighted Average Life	14 years		14 years
Other
Components of amortized intangible assets
Gross Carrying Amount	$ 7,918		$ 7,971
Accumulated Amortization	$ 6,887		$ 6,891
Weighted Average Life	5 years		5 years

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized in the remainder of the fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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