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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GOODWILL AND INTANGIBLE ASSETS - Amortized Intangible Assets - (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019	Dec. 28, 2019
Components of amortized intangible assets
Gross Carrying Amount	$ 265,243		$ 265,243		$ 269,748
Accumulated Amortization	162,450		162,450		163,113
Amortization expense for intangible assets	4,518	$ 4,484	13,621	$ 13,506
Estimated amortization expense
2020	17,687		17,687
2021	15,005		15,005
2022	13,027		13,027
2023	11,086		11,086
2024	9,446		9,446
Customer Relationships
Components of amortized intangible assets
Gross Carrying Amount	232,511		232,511		237,626
Accumulated Amortization	148,198		$ 148,198		$ 149,720
Weighted Average Life			13 years		13 years
Patents & Proprietary Technology
Components of amortized intangible assets
Gross Carrying Amount	25,240		$ 25,240		$ 24,068
Accumulated Amortization	7,699		$ 7,699		$ 6,358
Weighted Average Life			14 years		14 years
Other
Components of amortized intangible assets
Gross Carrying Amount	7,492		$ 7,492		$ 8,054
Accumulated Amortization	$ 6,553		$ 6,553		$ 7,035
Weighted Average Life			4 years		5 years