Segment Information and Geographical Data (Geographic Revenue before Reimbursements) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 28, 2025	Mar. 29, 2024
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 77,865	$ 77,187
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	64,011	64,751
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	8,355	7,993
Other (Australia, Canada, India and Uruguay) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 5,499	$ 4,443