Basis of Presentation (Details) $ in Thousands	3 Months Ended
	Dec. 29, 2018 USD ($) Segment	Dec. 30, 2017 USD ($)	Oct. 01, 2018 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments | Segment	2
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent	$ 1,321,169	$ 889,099		$ 874,589	$ 885,436
Deferred tax assets	201,149			165,566
Other income (expense), net	655	(798)
Accounting Standards Update 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred tax assets			$ 75,300
Other Tax Assets			6,000
Other Tax Liabilities			3,000
Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other income (expense), net	200
Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent	(138,785)	$ (637,519)		(599,409)	$ (650,840)
Accumulated Deficit | Accounting Standards Update 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent			$ 72,300
Other Current Assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted Cash	$ 1,100			$ 1,100