Revenue and Contract Balances - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 29, 2020	Mar. 31, 2019	Mar. 29, 2020	Mar. 31, 2019	Sep. 29, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract liability revenue recognized during the period			$ 105,000	$ 74,000
Revenue recognition net unfavorable operating income adjustments	$ 2,800		2,800
Liabilities for anticipated losses	14,600		14,600		$ 11,500
Estimated cost to complete the related contracts	57,000		$ 57,000
Period for billing and collecting unbilled receivables			12 months
Unbilled accounts receivable related to claims and requests for equitable adjustment on contracts	14,000		$ 14,000		$ 15,000
Remaining unsatisfied performance obligation	$ 2,972,097		$ 2,972,097
Remaining performance obligation, termination notice period one			30 days
Remaining performance obligation, termination notice period two			60 days
Remaining performance obligation, termination notice period three			90 days
RCM
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Recognized reduction of revenue		$ 4,800
Losses from claim settlement		5,900
CIG
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Recognized reduction of revenue		3,600
Losses from claim settlement		$ 3,600