Receivables (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 28, 2012	Sep. 28, 2012
Components of receivables:
Amounts billed	$ 1,119,114	$ 1,193,500
Unbilled receivables and other	1,060,652	1,110,008
Retentions receivable	44,093	45,384
Total receivables, net	2,223,859	2,348,892
Other information about receivables:
Amounts due from the United States federal government, included above, net of advanced billings	261,272	294,327
Claims receivable	$ 32,737	$ 26,309
Unbilled amounts billed and collected	12 months