Segment Information and Geographical Data (Narrative) (Details) $ in Thousands	6 Months Ended
	Jun. 27, 2025 USD ($) Segment	May 15, 2025 USD ($)	Dec. 27, 2024 USD ($)	Sep. 23, 2024 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | Segment	3
Number of reportable segments | Segment	3
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]	Chief Executive Officer [Member]
Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description	The CODM primarily uses revenue before reimbursement generated by the segment, cost of sales, gross margin, selling, general and administrative costs and contribution margin as a measure of profitability for each of its segments as these measures provide a comprehensive view of the segments’ financial performance. The measurement criteria for segment contribution is substantially the same for each reportable segment, excluding any unusual or infrequent items, if any.
Goodwill	$ 91,135		$ 89,782
Goodwill included in foreign assets	15,300		14,000
Global S&BT [Member]
Segment Reporting Information [Line Items]
Goodwill	64,443		63,090
United Kingdom [Member]
Segment Reporting Information [Line Items]
Goodwill	14,300		$ 13,100
United Kingdom [Member] | Global S&BT [Member]
Segment Reporting Information [Line Items]
Goodwill	5,800
Leewayhertz Technologies Private Limited [Member]
Segment Reporting Information [Line Items]
Goodwill				$ 5,876
Intangible assets	2,500			$ 2,500
Leewayhertz Technologies Private Limited [Member] | United States [Member]
Segment Reporting Information [Line Items]
Goodwill	5,800
Spend Matters LLC [Member]
Segment Reporting Information [Line Items]
Intangible assets		$ 2,000
Spend Matters LLC [Member] | United States [Member]
Segment Reporting Information [Line Items]
Intangible assets	$ 4,000