Revenue Accounting for Contracts - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Jan. 01, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 3,380,625	$ 3,381,836
United States
Disaggregation of Revenue [Line Items]
Revenues	2,148,554	2,457,041
Europe
Disaggregation of Revenue [Line Items]
Revenues	866,351	639,315
Canada
Disaggregation of Revenue [Line Items]
Revenues	65,039	55,627
Asia
Disaggregation of Revenue [Line Items]
Revenues	32,087	27,405
India
Disaggregation of Revenue [Line Items]
Revenues	22,148	14,548
Australia and New Zealand
Disaggregation of Revenue [Line Items]
Revenues	177,652	137,408
Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	$ 68,794	$ 50,492