Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenues:
Research	$ 440,271	$ 381,090
Consulting	84,940	76,792
Events	32,055	13,304
Total revenues	557,266	471,186
Costs and expenses:
Cost of services and product development	212,041	177,762
Selling, general and administrative	257,411	229,522
Depreciation	8,834	7,989
Amortization of intangibles	6,183	2,139
Acquisition and integration charges	8,368	5,092
Total costs and expenses	492,837	422,504
Operating income	64,429	48,682
Interest expense, net	(6,006)	(3,480)
Other income (expense), net	1,884	(962)
Income before income taxes	60,307	44,240
Provision for income taxes	20,140	15,889
Net income	$ 40,167	$ 28,351
Net income per share:
Basic (in Dollars per share)	$ 0.49	$ 0.33
Diluted (in Dollars per share)	$ 0.48	$ 0.32
Weighted average shares outstanding:
Basic (in shares)	82,451	86,539
Diluted (in shares)	83,464	87,773