Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Research services	$ 216,471	$ 215,216	$ 210,268
Advisory services and events	121,202	110,879	103,458
Total revenues	337,673	326,095	313,726
Operating expenses:
Cost of services and fulfillment	136,872	128,175	126,261
Selling and marketing	123,917	116,898	116,081
General and administrative	41,906	40,579	39,041
Depreciation	6,648	7,812	8,192
Amortization of intangible assets	781	831	891
Reorganization costs		1,026	4,433
Total operating expenses	310,124	295,321	294,899
Income from operations	27,549	30,774	18,827
Other income, net	301	740	511
Losses on investments, net	(479)	(805)	(18)
Income before income taxes	27,371	30,709	19,320
Income tax provision	12,231	13,058	7,324
Net income	$ 15,140	$ 17,651	$ 11,996
Basic income per common share	$ 0.84	$ 0.98	$ 0.67
Diluted income per common share	$ 0.83	$ 0.97	$ 0.66
Basic weighted average common shares outstanding	17,919	17,984	17,927
Diluted weighted average common shares outstanding	18,240	18,269	18,143