Restructuring Charges - Additional Information (Details) $ in Thousands	3 Months Ended		26 Months Ended
	Dec. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 30, 2017 USD ($) employee	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 105	$ 6,285	$ 85,500
Restructuring and Related Cost, Number of Positions Eliminated | employee			800
Restructuring Reserve	5,613	25,649	$ 5,613	$ 6,244	$ 36,608
Employee severance and related benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(212)	2,399
Restructuring Reserve	1,343	20,896	1,343	1,736	35,177
Facility closures and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	317	3,886
Restructuring Reserve	4,270	$ 4,753	4,270	$ 4,508	$ 1,431
Assumed Sublease Income	3,700		3,700
Accrued Expenses and Other Current Liabilities [Member] | Facility closures and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	2,200		2,200
Other Noncurrent Liabilities [Member] | Facility closures and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 2,100		$ 2,100