Accounts Receivable - Net and Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jul. 02, 2017	Jun. 26, 2016	Jul. 02, 2017	Jun. 26, 2016	Oct. 02, 2016
Net accounts receivable and billings in excess of costs on uncompleted contracts
Billed	$ 350,905		$ 350,905		$ 364,287
Unbilled	373,292		373,292		356,147
Contract retentions	38,488		38,488		29,135
Total accounts receivable - gross	762,685		762,685		749,569
Allowance for doubtful accounts	(31,394)		(31,394)		(35,233)
Total accounts receivable - net	731,291		731,291		714,336
Billings in excess of costs on uncompleted contracts	125,603		$ 125,603		88,223
Accounts Receivable - Net
Period for billing and collecting unbilled receivables			12 months
Period for earning majority of billings in excess of costs			12 months
Total accounts receivable related to claims, including requests for equitable adjustment on contracts	49,000		$ 49,000		45,000
Revenue Recognition and Contract Costs
Net unfavorable operating income adjustments			8,000
Liabilities for anticipated losses	8,700		8,700		6,700
Estimated cost to complete the related contracts	10,700		10,700
Accounts Receivable | U.S. federal government contracts
Accounts Receivable - Net
Billed accounts receivable related to U.S. federal government contracts	51,400		51,400		47,400
U.S. federal government unbilled receivables	95,700		95,700		$ 92,200
RCM
Accounts Receivable - Net
Reduction in the revenue related to the evaluation of the claims	400		4,900
Gains (losses) from claim settlement	$ (400)		(3,600)	$ 4,600
Cash proceeds from claim settlement				13,400
Claims amount		$ 8,800		8,800
Revenue Recognition and Contract Costs
Net unfavorable operating income adjustments		$ 2,300	5,700	$ 2,300
RME
Revenue Recognition and Contract Costs
Net unfavorable operating income adjustments			$ 2,300