Geographic and Group Information (Revenue By Service Group) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 28, 2019	Jun. 29, 2018	Jun. 28, 2019	Jun. 29, 2018
Segment Reporting Information [Line Items]
Revenue before reimbursements from continuing operations	$ 73,521	$ 74,527	$ 140,676	$ 145,634
Revenue Before Reimbursements [Member]
Segment Reporting Information [Line Items]
Revenue before reimbursements from continuing operations	67,976	68,706	130,346	134,745
S&BT [Member] \| Revenue Before Reimbursements [Member]
Segment Reporting Information [Line Items]
Revenue before reimbursements from continuing operations	35,718	37,816	68,988	72,955
EEA [Member] \| Revenue Before Reimbursements [Member]
Segment Reporting Information [Line Items]
Revenue before reimbursements from continuing operations	$ 32,258	$ 30,890	$ 61,358	$ 61,790

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration