Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues:
Research services	$ 202,998	$ 191,648	$ 168,508
Advisory services and other	89,932	91,968	82,218
Total revenues	292,930	283,616	250,726
Operating expenses:
Cost of services and fulfillment	111,228	103,571	94,105
Selling and marketing	101,390	101,468	84,663
General and administrative	36,866	33,284	33,960
Depreciation	8,921	5,359	3,628
Amortization of intangible assets	2,445	2,562	3,620
Reorganization costs	1,421	375
Total operating expenses	262,271	246,619	219,976
Income from operations	30,659	36,997	30,750
Other income, net	1,300	630	1,249
Gains (losses) on investments, net	(449)	1,018	2,301
Income before income taxes	31,510	38,645	34,300
Income tax provision	5,936	15,635	13,793
Net income	$ 25,574	$ 23,010	$ 20,507
Basic income per common share	$ 1.14	$ 1.02	$ 0.91
Diluted income per common share	$ 1.12	$ 0.99	$ 0.89
Basic weighted average common shares outstanding	22,500	22,666	22,478
Diluted weighted average common shares outstanding	22,929	23,164	23,063