Reportable Segments - Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 27, 2020	Jun. 28, 2020	Mar. 29, 2020	Dec. 29, 2019	Sep. 29, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 30, 2018	Sep. 27, 2020	Sep. 29, 2019	Sep. 30, 2018
Reportable Segments
Revenue	$ 753,364	$ 709,771	$ 734,133	$ 797,623	$ 841,502	$ 825,793	$ 722,621	$ 717,431	$ 2,994,891	$ 3,107,348	$ 2,964,148
United States
Reportable Segments
Revenue									2,107,457	2,247,780	2,232,013
Long-Lived Assets	230,933				51,859				230,933	51,859	57,256
Foreign countries
Reportable Segments
Revenue									887,434	859,568	732,135
Long-Lived Assets	$ 108,348				$ 46,113				$ 108,348	$ 46,113	$ 28,235