Goodwill and Intangible Assets - Goodwill (Details) $ in Thousands	6 Months Ended
	Apr. 01, 2018 USD ($)
Goodwill
Balance at beginning of the period	$ 740,886
Goodwill additions	81,001
Foreign exchange impact	(12,197)
Balance at end of the period	809,690
GSG
Goodwill
Balance at beginning of the period	361,761
Goodwill additions	26,726
Foreign exchange impact	(2,138)
Balance at end of the period	386,349
CIG
Goodwill
Balance at beginning of the period	379,125
Goodwill additions	54,275
Foreign exchange impact	(10,059)
Balance at end of the period	$ 423,341