Accounts Receivable - Net (Details) (USD $)	3 Months Ended
	Dec. 28, 2014	Sep. 28, 2014	Dec. 29, 2013
Accounts Receivable - Net
Billed	$ 337,791,000	$ 351,693,000
Unbilled	342,336,000	363,050,000
Contract retentions	23,621,000	26,929,000
Total accounts receivable - gross	703,748,000	741,672,000
Allowance for doubtful accounts	(36,323,000)	(39,780,000)
Total accounts receivable - net	667,425,000	701,892,000
Billings in excess of costs on uncompleted contracts	106,882,000	103,343,000
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 and requests for equitable adjustment on contracts	78,000,000	79,000,000
Revenue recognized related to the evaluation of claim amounts	3,200,000
Increase in operating income related to the evaluation of claim amounts	3,200,000
Billed accounts receivable related to U.S. federal government contracts	69,100,000	57,400,000
U.S. federal government unbilled receivables	67,800,000	73,200,000
Threshold percentage for disclosure of accounts receivable from a single client	10.00%	10.00%
Revenue Recognition and Contract Costs
Net unfavorable operating income adjustments	2,400,000		1,200,000
Liability for anticipated losses	16,800,000	18,600,000
Estimated cost to complete the related contracts	$ 99,100,000
Accounts Receivable
Account receivable major customer
Number of clients exceeding threshold	0	0