Accounts Receivable - Net (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2013	Apr. 01, 2012	Mar. 31, 2013 item	Apr. 01, 2012	Sep. 30, 2012 item
Accounts Receivable - Net
Billed	$ 351,897,000		$ 351,897,000		$ 362,331,000
Unbilled	343,416,000		343,416,000		355,793,000
Contract retentions	28,012,000		28,012,000		17,908,000
Total accounts receivable - gross	723,325,000		723,325,000		736,032,000
Allowance for doubtful accounts	(36,205,000)		(36,205,000)		(35,552,000)
Total accounts receivable - net	687,120,000		687,120,000		700,480,000
Current billings in excess of costs on uncompleted contracts	79,131,000		79,131,000		90,909,000
Non-current billings in excess of costs on uncompleted contracts	1,474,000		1,474,000		4,410,000
Total billings in excess of costs on uncompleted contracts	80,605,000		80,605,000		95,319,000
Period for billing and collecting unbilled receivables			12 months
Unbilled accounts receivable related to claims and requests for equitable adjustment on contracts	36,000,000		36,000,000		21,000,000
Loss on uncollectible accounts receivable related to claims	0	0	0	0
Period for earning majority of billings in excess of costs			12 months
Billed accounts receivable related to U.S. federal government contracts	66,400,000		66,400,000		65,900,000
U.S. federal government unbilled receivables, net of progress payments	$ 83,400,000		$ 83,400,000		$ 100,400,000
Number of clients exceeding threshold			0		0
Threshold percentage for disclosure of accounts receivable from a single client			10.00%		10.00%