CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenue		$ 305,301	$ 306,520	$ 907,988	$ 895,538
Direct Costs		189,992	191,310	564,495	562,697
Operating costs and expenses:
Indirect and selling expenses		84,558	84,193	259,600	250,393
Depreciation and amortization		4,613	4,130	13,431	12,233
Amortization of intangible assets		2,742	3,111	8,225	9,387
Total operating costs and expenses		91,913	91,434	281,256	272,013
Operating income		23,396	23,776	62,237	60,828
Interest expense		(2,175)	(2,407)	(6,663)	(7,312)
Other (expense) income		(311)	732	24	950
Income before income taxes		20,910	22,101	55,598	54,466
Provision for income taxes		7,218	8,664	19,792	20,555
Net income		$ 13,692	$ 13,437	$ 35,806	$ 33,911
Earnings per Share:
Basic		$ 0.73	$ 0.71	$ 1.90	$ 1.79
Diluted		$ 0.72	$ 0.70	$ 1.86	$ 1.75
Weighted-average Shares:
Basic		18,666	18,965	18,807	18,989
Diluted		19,024	19,329	19,218	19,345
Other comprehensive income (loss), net of tax	[1]	$ 558	$ (165)	$ 3,030	$ (3,108)
Comprehensive income, net of tax		$ 14,250	$ 13,272	$ 38,836	$ 30,803

[1] Net of tax of $0.6 million and $1.6 million for the three months ended September 30, 2017 and 2016, respectively, and $1.3 million and $3.0 million for the nine months ended September 30, 2017 and 2016, respectively.