Goodwill and Intangible Assets - Goodwill (Details) $ in Thousands	9 Months Ended
	Jun. 28, 2020 USD ($)
Goodwill
Balance at beginning of the period	$ 924,820
Acquisition activity	40,814
Translation	(7,472)
Balance at end of the period	958,162
GSG
Goodwill
Balance at beginning of the period	441,802
Acquisition activity	35,520
Translation	(2,858)
Balance at end of the period	474,464
CIG
Goodwill
Balance at beginning of the period	483,018
Acquisition activity	5,294
Translation	(4,614)
Balance at end of the period	$ 483,698