CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenue	$ 373,918	$ 332,968	$ 1,081,889	$ 960,063
Direct costs	238,158	213,060	689,160	608,451
Operating costs and expenses:
Indirect and selling expenses	100,130	88,960	298,099	269,029
Depreciation and amortization	5,035	4,210	15,392	12,724
Amortization of intangible assets	1,931	2,516	6,143	7,030
Total operating costs and expenses	107,096	95,686	319,634	288,783
Operating income	28,664	24,222	73,095	62,829
Interest expense	(2,824)	(2,240)	(8,211)	(6,073)
Other expense	(141)	(351)	(367)	(565)
Income before income taxes	25,699	21,631	64,517	56,191
Provision for income taxes	6,069	4,960	14,958	13,486
Net income	$ 19,630	$ 16,671	$ 49,559	$ 42,705
Earnings per Share:
Basic	$ 1.04	$ 0.88	$ 2.63	$ 2.27
Diluted	$ 1.02	$ 0.86	$ 2.58	$ 2.22
Weighted-average Shares:
Basic	18,799	18,873	18,810	18,783
Diluted	19,169	19,306	19,208	19,256
Cash dividends declared per common share	$ 0.14	$ 0.14	$ 0.42	$ 0.42
Other comprehensive loss, net of tax	$ (3,281)	$ (568)	$ (5,851)	$ (2,276)
Comprehensive income, net of tax	$ 16,349	$ 16,103	$ 43,708	$ 40,429