Accounts Receivable - Net (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 30, 2012 M	Sep. 30, 2012
Accounts Receivable - Net
Billed	$ 370,231,000	$ 362,331,000
Unbilled	325,305,000	355,793,000
Contract retentions	16,047,000	17,908,000
Total accounts receivable - gross	711,583,000	736,032,000
Allowance for doubtful accounts	(36,689,000)	(35,552,000)
Total accounts receivable - net	674,894,000	700,480,000
Current billings in excess of costs on uncompleted contracts	94,511,000	90,909,000
Non-current billings in excess of costs on uncompleted contracts	4,351,000	4,410,000
Total billings in excess of costs on uncompleted contracts	98,862,000	95,319,000
Period for billing and collecting unbilled receivables (in months)	12
Unbilled accounts receivable related to claims and requests for equitable adjustment on contracts	17,000,000	21,000,000
Period for earning majority of billings in excess of costs (in months)	12
Billed accounts receivable related to U.S. federal government contracts	72,700,000	65,900,000
U.S. federal government unbilled receivables, net of progress payments	$ 104,100,000	$ 100,400,000
Threshold percentage for disclosure of accounts receivable from a single client	10.00%	10.00%