Goodwill and Intangibles - Schedule of Acquired Intangibles in Accompanying Consolidated Balance Sheets (Details) $ in Thousands	9 Months Ended
	Jun. 26, 2020 USD ($)
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	$ 665,076
Amortization	(67,074)
Acquired	80,010
Foreign currency translation	(2,007)
Ending balance	676,005
Customer Relationships, Contracts and Backlog
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	622,392
Amortization	(64,002)
Acquired	73,558
Foreign currency translation	(1,170)
Ending balance	630,778
Developed Technology
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	40,833
Amortization	(2,751)
Acquired	6,452
Foreign currency translation	(232)
Ending balance	44,302
Trade Names
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	1,183
Amortization	(321)
Acquired	0
Foreign currency translation	(54)
Ending balance	808
Other
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	668
Amortization	0
Acquired	0
Foreign currency translation	(551)
Ending balance	$ 117