Goodwill and Intangibles - Schedule of Carrying Value of Goodwill by Reportable Segment Appearing in Accompanying Consolidated Balance Sheets (Details) $ in Thousands	6 Months Ended
	Mar. 29, 2019 USD ($)
Goodwill [Roll Forward]
September 28, 2018	$ 4,795,856
Post-Acquisition Adjustments	(14,000)
Foreign Exchange Impact	(7,000)
March 29, 2019	4,774,849
Aerospace, Technology and Nuclear
Goodwill [Roll Forward]
September 28, 2018	1,581,000
Post-Acquisition Adjustments	(10,000)
Foreign Exchange Impact	(2,000)
March 29, 2019	1,569,000
Buildings, Infrastructure and Advanced Facilities
Goodwill [Roll Forward]
September 28, 2018	3,215,000
Post-Acquisition Adjustments	(4,000)
Foreign Exchange Impact	(5,000)
March 29, 2019	$ 3,206,000