Revenue Accounting for Contracts - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 26, 2020	Jun. 28, 2019	Jun. 26, 2020	Jun. 28, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 3,260,057	$ 3,169,622	$ 10,047,286	$ 9,345,005
United States
Disaggregation of Revenue [Line Items]
Revenues	2,472,091	2,357,836	7,548,192	6,701,474
Europe
Disaggregation of Revenue [Line Items]
Revenues	504,201	491,036	1,662,104	1,706,163
Canada
Disaggregation of Revenue [Line Items]
Revenues	56,954	59,830	164,601	160,339
Asia
Disaggregation of Revenue [Line Items]
Revenues	27,995	33,918	90,889	113,294
India
Disaggregation of Revenue [Line Items]
Revenues	16,465	12,129	33,229	43,131
Australia and New Zealand
Disaggregation of Revenue [Line Items]
Revenues	130,133	136,711	378,178	386,594
South America and Mexico
Disaggregation of Revenue [Line Items]
Revenues	0	1,225	0	7,244
Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	$ 52,218	$ 76,937	$ 170,093	$ 226,766