UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Net service revenues	$ 335,047	$ 337,353	$ 657,248	$ 649,964
Direct costs of services	228,765	231,315	453,777	449,186
Gross profit	106,282	106,038	203,471	200,778
Selling, general and administrative expenses	85,587	83,195	171,155	165,547
Depreciation and amortization	2,252	2,426	4,579	4,823
Income from operations	18,443	20,417	27,737	30,408
Other expense, net	718	991	1,273	1,444
Income before income taxes	17,725	19,426	26,464	28,964
Income tax expense	6,861	7,833	11,950	11,586
Net income	10,864	11,593	14,514	17,378
Other comprehensive (loss) income:
Defined benefit pension plans, net of tax	(2)	1	(5)	2
Comprehensive income	$ 10,862	$ 11,594	$ 14,509	$ 17,380
Earnings per share – basic (in dollars per share)	$ 0.41	$ 0.41	$ 0.55	$ 0.62
Earnings per share – diluted (in dollars per share)	$ 0.41	$ 0.41	$ 0.55	$ 0.61
Weighted average shares outstanding – basic (in shares)	26,180	28,134	26,436	28,204
Weighted average shares outstanding – diluted (in shares)	26,335	28,337	26,587	28,407
Dividends declared per share (in dollars per share)	$ 0.12	$ 0.11	$ 0.24	$ 0.22