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Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 27, 2020	Mar. 29, 2019	Mar. 27, 2020	Mar. 29, 2019	Oct. 01, 2019	Sep. 30, 2019
Goodwill [Line Items]
Intangible asset amortization	$ 8,071	$ 8,196	$ 16,184	$ 16,410
Goodwill	186,779		186,779			$ 186,231
Electrical Raceway
Goodwill [Line Items]
Accumulated impairment loss	3,924		3,924		$ 3,924
Goodwill	150,216		150,216			149,668
MP&S
Goodwill [Line Items]
Accumulated impairment loss	43,000		43,000		$ 43,000
Goodwill	$ 36,563		$ 36,563			$ 36,563
EMEA
Goodwill [Line Items]
Percentage of fair value in excess of carrying amount (less than)	10.00%		10.00%
Goodwill	$ 35,029		$ 35,029