Consolidated Statements Of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Consolidated Statements Of Comprehensive Income [Abstract]
Revenues before reimbursements	$ 236,211	$ 223,475
Reimbursements	21,626	21,812
Total revenues	257,837	245,287
Cost of services before reimbursable expenses	165,052	153,940
Reimbursable expenses	21,626	21,812
Total costs of services	186,678	175,752
General and administrative expenses	41,484	39,831
Depreciation expense	7,473	6,522
Amortization expense	2,319	2,921
Other operating costs (benefit):
Contingent acquisition liability adjustments, net	1,199
Office consolidation, net	(38)
Deferred debt issuance costs write off	145
Operating income	18,577	20,261
Interest expense	1,069	1,260
Interest income	(31)	(39)
Other income, net	(217)	(340)
Income before income tax expense	17,756	19,380
Income tax expense	6,660	6,738
Net income	$ 11,096	$ 12,642
Basic net income per share	$ 0.24	$ 0.27
Shares used in computing basic per share data	46,932	47,425
Diluted net income per share	$ 0.23	$ 0.26
Shares used in computing diluted per share data	48,969	49,031
Net income	$ 11,096	$ 12,642
Other comprehensive income (loss), net of tax
Unrealized net gain (loss), foreign currency translation	830	(530)
Unrealized net gain (loss) on interest rate derivatives	11	(162)
Reclassification adjustment on interest rate derivatives included in interest expense and income tax expense	20	52
Other comprehensive income (loss), net of tax	861	(640)
Total comprehensive income, net of tax	$ 11,957	$ 12,002