Goodwill and Intangibles - Schedule of Carrying Value of Goodwill by Reportable Segment Appearing in Accompanying Consolidated Balance Sheets (Details) $ in Thousands	9 Months Ended
	Jun. 26, 2020 USD ($)
Goodwill [Roll Forward]
Balance at the beginning of the period	$ 5,432,544
Acquired	206,000
Foreign Exchange Impact	(18,000)
Post-Acquisition Adjustments	2,000
Disposed	(6,000)
Balance at the end of the period	5,616,849
Critical Mission Solutions
Goodwill [Roll Forward]
Balance at the beginning of the period	2,202,000
Acquired	206,000
Foreign Exchange Impact	(10,000)
Post-Acquisition Adjustments	2,000
Disposed	0
Balance at the end of the period	2,400,000
People & Places Solutions
Goodwill [Roll Forward]
Balance at the beginning of the period	3,231,000
Acquired	0
Foreign Exchange Impact	(8,000)
Post-Acquisition Adjustments	0
Disposed	(6,000)
Balance at the end of the period	$ 3,217,000