Consolidated Statements of Income (Loss) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Total revenues	$ 461,697	$ 357,575	$ 337,673
Operating expenses:
Selling and marketing	172,865	131,824	123,917
General and administrative	53,042	43,920	41,906
Depreciation	8,572	7,955	6,648
Amortization of intangible assets	22,619	1,162	781
Acquisition and integration costs	8,948	3,787
Total operating expenses	462,772	335,150	310,124
Income (loss) from operations	(1,075)	22,425	27,549
Interest expense	(8,054)
Other income (expense), net	(515)	674	301
Gains (losses) on investments, net	45	426	(479)
Income (loss) before income taxes	(9,599)	23,525	27,371
Income tax expense (benefit)	(29)	8,145	12,231
Net income (loss)	$ (9,570)	$ 15,380	$ 15,140
Basic income (loss) per common share	$ (0.52)	$ 0.85	$ 0.84
Diluted income (loss) per common share	$ (0.52)	$ 0.84	$ 0.83
Basic weighted average common shares outstanding	18,492	18,091	17,919
Diluted weighted average common shares outstanding	18,492	18,380	18,240
Research Services [Member]
Revenues:
Total revenues	$ 298,735	$ 228,399	$ 216,471
Advisory Services and Events [Member]
Revenues:
Total revenues	162,962	129,176	121,202
Cost of Services and Fulfillment [Member]
Operating expenses:
Cost of services and fulfillment	$ 196,726	$ 146,502	$ 136,872