Segment Information and Geographical Data (Geographic Revenue before Reimbursements) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Apr. 01, 2022
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 71,229	$ 75,664
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	61,351	64,393
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	6,060	7,537
Other (Australia, Canada, India and Uruguay) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 3,818	$ 3,734