Long-Term Debt (Parenthetical) (Detail)	9 Months Ended	12 Months Ended
	Jun. 29, 2018	Sep. 29, 2017	Apr. 30, 2015
3.625% Senior Notes, due April 2023
Debt Instrument [Line Items]
Long-term debt interest rate	3.625%	3.625%	3.625%
Debt instruments maturity period	2023-04	2023-04
U.S. Term Loan, due April 2020
Debt Instrument [Line Items]
Debt instruments maturity period	2020-04	2020-04