Revenue Accounting for Contracts - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 27, 2020	Mar. 29, 2019	Mar. 27, 2020	Mar. 29, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 3,427,180	$ 3,091,596	$ 6,787,229	$ 6,175,384
United States
Disaggregation of Revenue [Line Items]
Revenues	2,543,387	2,161,334	5,076,101	4,343,638
Europe
Disaggregation of Revenue [Line Items]
Revenues	606,630	600,903	1,157,903	1,215,127
Canada
Disaggregation of Revenue [Line Items]
Revenues	52,251	50,021	107,647	100,509
Asia
Disaggregation of Revenue [Line Items]
Revenues	32,454	43,765	62,894	79,376
India
Disaggregation of Revenue [Line Items]
Revenues	10,784	18,364	16,764	31,002
Australia and New Zealand
Disaggregation of Revenue [Line Items]
Revenues	118,850	123,235	248,045	249,883
South America and Mexico
Disaggregation of Revenue [Line Items]
Revenues	0	3,370	0	6,020
Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	$ 62,824	$ 90,604	$ 117,875	$ 149,829