Accounts Receivable - Net (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 27, 2015 USD ($)	Mar. 29, 2015 USD ($)	Mar. 27, 2016 USD ($) item	Mar. 29, 2015 USD ($)	Sep. 27, 2015 USD ($)
Account receivable major customer
Threshold percentage for disclosure of accounts receivable from a single client			10.00%		10.00%
Accounts Receivable, Net
Billed			$ 348,360		$ 331,364
Unbilled			342,828		311,823
Contract retentions			28,695		24,333
Total accounts receivable - gross			719,883		667,520
Allowance for doubtful accounts			(38,760)		(31,490)
Total accounts receivable - net			681,123		636,030
Billings in excess of costs on uncompleted contracts			$ 92,125		93,989
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			$ 42,000		53,000
Gain from claim settlement				$ 200
Revenue recognized related to the evaluation of claim amounts		$ (3,000)
Decrease in operating income related to the evaluation of claim amounts		3,000
Billed accounts receivable related to U.S. federal government contracts			56,800		61,900
U.S. federal government unbilled receivables			76,000		74,200
Revenue Recognition and Contract Costs
Net unfavorable operating income adjustments		$ 3,500		$ 5,900
Liability for anticipated losses			7,900		$ 10,500
Estimated cost to complete the related contracts			$ 36,700
Accounts Receivable | International
Account receivable major customer
Number of clients exceeding threshold | item			1
RCM
Accounts Receivable, Net
Cash proceeds from claim settlement	$ 13,400		$ 13,400
Claims amount	8,800		8,800
Gain from claim settlement	4,600		4,600
Decrease in operating income related to the increase in allowance for doubtful accounts	7,900		7,900
Increase in allowance for doubtful accounts	7,900		7,900
Collectability of certain accounts receivable	$ 4,600		$ 4,600