Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Revenues:
Research	$ 255,979	$ 214,680	$ 749,429	$ 634,448
Consulting	70,815	65,397	219,407	212,796
Events	18,990	16,045	72,058	58,906
Total revenues	345,784	296,122	1,040,894	906,150
Costs and expenses:
Cost of services and product development	142,696	125,897	428,473	387,279
Selling, general and administrative	148,461	127,488	442,891	388,378
Depreciation	6,638	6,194	19,143	19,218
Amortization of intangibles	739	2,531	5,788	7,994
Acquisition and integration charges		1,249		7,090
Total costs and expenses	298,534	263,359	896,295	809,959
Operating income	47,250	32,763	144,599	96,191
Interest expense, net	(2,282)	(3,005)	(7,863)	(9,569)
Other (expense) income, net	(541)	(373)	(1,494)	736
Income before income taxes	44,427	29,385	135,242	87,358
Provision for income taxes	13,963	9,310	43,364	27,767
Net income	$ 30,464	$ 20,075	$ 91,878	$ 59,591
Income per common share:
Basic	$ 0.32	$ 0.21	$ 0.95	$ 0.62
Diluted	$ 0.31	$ 0.20	$ 0.92	$ 0.60
Weighted average shares outstanding:
Basic	96,057	95,473	96,462	95,698
Diluted	98,259	98,797	99,467	99,584