UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenue	$ 363,225	$ 335,208
Direct costs	264,543	240,684
Gross profit	98,682	94,524
Selling, general and administrative expenses	78,029	79,216
Depreciation and amortization	1,202	1,393
Income from operations	19,451	13,915
Other expense, net	1,285	1,381
Income from operations, before income taxes	18,166	12,534
Income tax expense	4,905	3,428
Net income	13,261	9,106
Other comprehensive loss:
Defined benefit pension plans, no tax benefit	47	0
Change in fair value of interest rate swaps, net of tax	939	(1,121)
Comprehensive income	$ 14,247	$ 7,985
Earnings per share – basic (in dollars per share)	$ 0.63	$ 0.42
Earnings per share - diluted (in dollars per share)	$ 0.62	$ 0.42
Weighted average shares outstanding – basic (in shares)	20,932	21,553
Weighted average shares outstanding – diluted (in shares)	21,361	21,860