Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue	$ 165,236	$ 146,815	$ 479,302	$ 462,950
Cost of services:
Compensation	63,829	56,258	193,678	172,033
Direct project and other operating expenses	23,335	22,751	71,214	63,693
Information technology	15,160	14,207	45,188	39,627
Occupancy	3,965	4,144	12,517	12,275
Amortization of acquisition related software and intangible assets	5,506	4,158	16,575	12,490
Total cost of services	111,795	101,518	339,172	300,118
Selling, general and administrative expenses	26,241	28,232	88,861	85,514
Total operating expenses	138,036	129,750	428,033	385,632
Operating income	27,200	17,065	51,269	77,318
Interest expense	(1,926)	(2,677)	(6,135)	(8,379)
Interest income	8	1,210	266	3,291
Other (expense)/income	(1,127)	7,697	1,744	7,697
Income before income taxes	24,155	23,295	47,144	79,927
Income taxes	6,120	2,159	9,814	10,049
Net income	$ 18,035	$ 21,136	$ 37,330	$ 69,878
Basic income per common share:
Net income per common share -- basic (in dollars per share)	$ 0.20	$ 0.24	$ 0.42	$ 0.79
Diluted income per common share:
Net income per common share -- diluted (in dollars per share)	$ 0.20	$ 0.24	$ 0.42	$ 0.77
Weighted average shares:
Basic (in shares)	88,531	86,324	88,397	88,190
Diluted (in shares)	90,228	88,324	89,976	90,441