Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Revenue	$ 1,553,048	$ 1,506,875	$ 1,478,525
Direct costs	979,570	972,406	953,187
Operating costs and expenses
Indirect and selling expenses	430,572	411,612	395,763
Depreciation and amortization	19,478	20,399	20,099
Amortization of intangible assets	12,492	13,349	8,083
Total operating costs and expenses	462,542	445,360	423,945
Operating income	110,936	89,109	101,393
Interest expense	(10,252)	(13,892)	(10,719)
Other expense	(594)	(544)	(501)
Income before income taxes	100,090	74,673	90,173
Provision for income taxes	28,958	19,714	21,235
Net income	$ 71,132	$ 54,959	$ 68,938
Earnings per share:
Basic	$ 3.77	$ 2.92	$ 3.66
Diluted	$ 3.72	$ 2.87	$ 3.59
Weighted-average common shares outstanding:
Basic	18,868	18,841	18,816
Diluted	19,124	19,135	19,224
Cash dividends declared per common share	$ 0.56	$ 0.56	$ 0.56
Other comprehensive income (loss), net of tax	$ 3,071	$ (1,962)	$ 407
Comprehensive income, net of tax	$ 74,203	$ 52,997	$ 69,345