Summary of Significant Accounting Policies and Recently Issued Accounting Standards Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jan. 04, 2020	Oct. 03, 2020	Sep. 28, 2019	Jul. 04, 2020	Apr. 04, 2020	Jun. 29, 2019	Mar. 30, 2019	Sep. 30, 2018	Sep. 29, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Percentage of active participants (less than)	10.00%
Amortization period of deferred pension losses			7 years
Adoption of new revenue recognition standard (ASC 606) adjustment			$ (67,811)	$ (61,928)	$ (65,063)	$ (61,186)	$ (77,590)		$ (28,336)
Accounting Standards Update 2014-09 | Cumulative Effect, Period of Adoption, Adjustment
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Adoption of new revenue recognition standard (ASC 606) adjustment								$ (714)
Scenario, Forecast | Subsequent Event
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Amortization period of deferred pension losses		23 years