CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Revenue	$ 1,531,756	$ 1,710,765	$ 1,579,922
Direct costs	1,104,690	1,209,658	1,123,058
Gross profit	427,066	501,107	456,864
Selling, general and administrative expenses	334,933	379,815	345,721
Depreciation and amortization	5,012	4,427	4,500
Income from operations	87,121	116,865	106,643
Other expense, net	1,871	14,423	7,376
Income from operations, before income taxes	85,250	102,442	99,267
Income tax expense	24,175	27,011	24,090
Net income	61,075	75,431	75,177
Other comprehensive (loss) income:
Defined benefit pension plans, net of tax	0	0	3,103
Change in fair value of interest rate swaps, net of tax	0	(615)	1,941
Comprehensive income	$ 61,075	$ 74,816	$ 80,221
Weighted average shares outstanding - basic (in shares)	19,188	20,054	20,579
Weighted average shares outstanding – diluted (in shares)	19,507	20,503	21,212
Earnings per share – basic (in dollars per share)	$ 3.18	$ 3.76	$ 3.65
Diluted (in dollars per share)	$ 3.13	$ 3.68	$ 3.54