UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Statement [Abstract]
Revenue	$ 416,967	$ 363,225
Direct costs	293,081	264,543
Gross profit	123,886	98,682
Selling, general and administrative expenses	95,049	78,029
Depreciation and amortization	1,093	1,202
Income from operations	27,744	19,451
Other expense, net	1,433	1,285
Income from operations, before income taxes	26,311	18,166
Income tax expense	7,130	4,905
Net income	19,181	13,261
Other comprehensive income, net of tax:
Defined benefit pension plans	0	47
Change in fair value of interest rate swaps	2,302	939
Comprehensive income	$ 21,483	$ 14,247
Earnings per share – basic (in dollars per share)	$ 0.94	$ 0.63
Earnings per share - diluted (in dollars per share)	$ 0.93	$ 0.62
Weighted average shares outstanding – basic (in shares)	20,319	20,932
Weighted average shares outstanding – diluted (in shares)	20,730	21,361