Consolidated Statements of operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Total revenues	$ 448,984	$ 461,697	$ 357,575
Operating expenses:
Selling and marketing	166,200	172,865	131,824
General and administrative	50,369	53,042	43,920
Depreciation	9,879	8,572	7,955
Amortization of intangible assets	19,683	22,619	1,162
Acquisition and integration costs	5,779	8,948	3,787
Total operating expenses	432,809	462,772	335,150
Income (loss) from operations	16,175	(1,075)	22,425
Interest expense	(5,340)	(8,054)
Other income (expense), net	(374)	(515)	674
Gains on investments, net	2,472	45	426
Income (loss) before income taxes	12,933	(9,599)	23,525
Income tax expense (benefit)	2,943	(29)	8,145
Net income (loss)	$ 9,990	$ (9,570)	$ 15,380
Basic income (loss) per common share	$ 0.53	$ (0.52)	$ 0.85
Diluted income (loss) per common share	$ 0.53	$ (0.52)	$ 0.84
Basic weighted average common shares outstanding	18,827	18,492	18,091
Diluted weighted average common shares outstanding	18,935	18,492	18,380
Research [Member]
Revenues:
Total revenues	$ 294,485	$ 298,735	$ 228,399
Consulting [Member]
Revenues:
Total revenues	144,362	135,952	115,705
Events [Member]
Revenues:
Total revenues	10,137	27,010	13,471
Cost of Services and Fulfillment [Member]
Operating expenses:
Cost of services and fulfillment	$ 180,899	$ 196,726	$ 146,502