Accounts Receivable - Net and Revenue Recognition (Details) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Oct. 01, 2017
Accounts Receivable - Net and Revenue Recognition
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	$ 61,000,000		$ 59,000,000
Gains (losses) from claim settlement	0	$ 0
Billed accounts receivable related to U.S. federal government contracts	65,000,000		45,400,000
U.S. federal government unbilled receivables	$ 116,800,000		$ 109,700,000
Threshold percentage for disclosure of accounts receivable from a single client	10.00%		10.00%
Net unfavorable operating income adjustments		4,000,000
Liabilities for anticipated losses	$ 4,500,000		$ 8,100,000
Estimated cost to complete the related contracts	4,700,000
CIG
Accounts Receivable - Net and Revenue Recognition
Net unfavorable operating income adjustments	$ 700,000	2,300,000
RCM
Accounts Receivable - Net and Revenue Recognition
Net unfavorable operating income adjustments		$ 1,700,000