Accounts Receivable - Net (Details) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Jun. 26, 2016 USD ($)	Dec. 27, 2015 USD ($)	Jun. 28, 2015 USD ($) claim	Jun. 26, 2016 USD ($)	Jun. 28, 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	$ 367,632			$ 367,632		$ 331,364
Unbilled	338,207			338,207		311,823
Contract retentions	34,680			34,680		24,333
Total accounts receivable - gross	740,519			740,519		667,520
Allowance for doubtful accounts	(39,673)			(39,673)		(31,490)
Total accounts receivable - net	700,846			700,846		636,030
Billings in excess of costs on uncompleted contracts	93,401			$ 93,401		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	43,000			$ 43,000		53,000
Gain (loss) from claim settlement					$ (1,800)
Revenue recognized related to the evaluation of claim amounts			$ (2,000)
Decrease in operating income related to the evaluation of claim amounts			$ 2,000
Billed accounts receivable related to U.S. federal government contracts	50,700			50,700		61,900
U.S. federal government unbilled receivables	82,900			82,900		74,200
Revenue Recognition and Contract Costs
Liability for anticipated losses	5,400			5,400		$ 10,500
Estimated cost to complete the related contracts	34,600			34,600
RCM
Accounts Receivable, Net
Number of claims settled | claim			2
Cash proceeds from claim settlement		$ 13,400	$ 29,000	13,400
Claims amount	8,800	8,800	31,000	8,800	31,000
Gain (loss) 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
Revenue Recognition and Contract Costs
Net unfavorable operating income adjustments	$ 2,300		$ 100	$ 2,300	$ 5,800