Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues:
Total revenues	$ 113,541	$ 128,183	$ 219,886	$ 228,832
Operating expenses:
Selling and marketing	39,117	44,017	79,390	86,050
General and administrative	11,456	13,221	23,461	26,411
Depreciation	2,448	2,166	4,854	4,189
Amortization of intangible assets	4,713	5,099	9,425	11,309
Acquisition and integration costs	612	2,487	3,487	5,454
Total operating expenses	102,310	123,561	207,934	235,094
Income (loss) from operations	11,231	4,622	11,952	(6,262)
Interest expense	(1,307)	(2,085)	(2,845)	(4,437)
Other income (expense), net	(201)	(86)	109	(356)
Gain (loss) on investments, net	2,352	(8)	2,365	(44)
Income (loss) before income taxes	12,075	2,443	11,581	(11,099)
Income tax expense	238	888	257	662
Net income (loss)	$ 11,837	$ 1,555	$ 11,324	$ (11,761)
Basic income (loss) per common share	$ 0.63	$ 0.08	$ 0.60	$ (0.64)
Diluted income (loss) per common share	$ 0.63	$ 0.08	$ 0.60	$ (0.64)
Basic weighted average common shares outstanding	18,759	18,435	18,732	18,399
Diluted weighted average common shares outstanding	18,831	18,780	18,828	18,399
Research [Member]
Revenues:
Total revenues	$ 73,621	$ 76,279	$ 146,417	$ 144,888
Consulting [Member]
Revenues:
Total revenues	34,888	34,017	68,347	65,803
Events [Member]
Revenues:
Total revenues	5,032	17,887	5,122	18,141
Cost of Services and Fulfillment [Member]
Operating expenses:
Cost of services and fulfillment	$ 43,964	$ 56,571	$ 87,317	$ 101,681