Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2018	Sep. 29, 2017
Revenues:
Revenues before reimbursements	$ 88,714	$ 82,359	$ 269,370	$ 246,946
Reimbursements	6,588	5,196	18,010	12,571
Revenues	95,302	87,555	287,380	259,517
Operating expenses:
Compensation and related expenses	55,639	51,493	168,676	157,447
Other operating expenses	7,826	7,500	22,857	21,966
Reimbursable expenses	6,588	5,196	18,010	12,571
General and administrative expenses	4,655	4,061	13,167	13,277
Total operating expenses	74,708	68,250	222,710	205,261
Operating income	20,594	19,305	64,670	54,256
Other income, net:
Interest income, net	740	372	1,813	872
Miscellaneous income, net	2,655	2,353	4,875	6,660
Total other income, net	3,395	2,725	6,688	7,532
Income before income taxes	23,989	22,030	71,358	61,788
Income taxes	6,536	7,387	15,140	16,778
Net income	$ 17,453	$ 14,643	$ 56,218	$ 45,010
Net income per share:
Basic	$ 0.33	$ 0.28	$ 1.06	$ 0.85
Diluted	$ 0.32	$ 0.27	$ 1.04	$ 0.83
Shares used in per share computations:
Basic	53,032	52,740	52,928	52,724
Diluted	54,302	53,926	54,181	53,952
Cash dividends declared per common share	$ 0.130	$ 0.105	$ 0.390	$ 0.315