Business Segments and Geographic Information - Revenues by Geography (Detail)	3 Months Ended
	Dec. 28, 2019	Dec. 29, 2018
Schedule Of Geographical Segments [Line Items]
Revenues	100.00%	100.00%
United States
Schedule Of Geographical Segments [Line Items]
Revenues	74.40%	74.90%
Europe
Schedule Of Geographical Segments [Line Items]
Revenues	12.90%	12.20%
Asia-Pacific
Schedule Of Geographical Segments [Line Items]
Revenues	8.30%	8.40%
Rest of World
Schedule Of Geographical Segments [Line Items]
Revenues	4.40%	4.50%