Accounts Receivable - Net and Revenue Recognition (Details) $ in Thousands	12 Months Ended
	Oct. 02, 2016 USD ($)	Sep. 27, 2015 USD ($) claim
Billed	$ 364,287	$ 331,364
Unbilled	356,147	311,823
Contract retentions	29,135	24,333
Total accounts receivable - gross	749,569	667,520
Allowance for doubtful accounts	(35,233)	(31,490)
Total accounts receivable - net	714,336	636,030
Billings in excess of costs on uncompleted contracts	$ 88,223	93,989
Period for billing and collecting unbilled receivables	12 months
Period for earning majority of billings in excess of costs	12 months
Unbilled accounts receivable related to claims and requests for equitable adjustment on contracts	$ 45,000	53,000
Billed accounts receivable related to U.S. federal government contracts	47,400	61,900
U.S. federal government unbilled receivables	$ 92,200	$ 74,200
Threshold percentage for disclosure of accounts receivable from a single client	10.00%	10.00%
RCM
Cash proceeds from claim settlement	$ 13,400	$ 29,000
Claims settlement amount	8,800	$ 31,000
Decrease in operating income related to the increase in allowance for doubtful accounts	7,900
Increase in allowance for doubtful accounts	7,900
Collectability of certain accounts receivable	4,600
Number of claims settled | claim		2
Decrease in operating income resulted from settlement of claims		$ 2,000
Revenue recognized resulted from settlement of claims		$ (2,000)
Gain (loss) from claim settlement	$ 4,600