Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues:
Research	$ 613,732	$ 456,690	$ 1,125,038	$ 904,280
Consulting	91,693	86,548	170,287	164,169
Events	91,205	66,760	126,474	98,815
Talent Assessment & Other	47,101	0	47,101	0
Total revenues	843,731	609,998	1,468,900	1,167,264
Costs and expenses:
Cost of services and product development	352,004	231,422	589,613	443,463
Selling, general and administrative	408,226	272,009	712,470	529,420
Depreciation	18,057	9,025	28,297	17,859
Amortization of intangibles	65,500	6,210	71,790	12,393
Acquisition and integration charges	98,332	8,033	111,604	16,401
Total costs and expenses	942,119	526,699	1,513,774	1,019,536
Operating (loss) income	(98,388)	83,299	(44,874)	147,728
Interest expense, net	(43,956)	(7,356)	(49,862)	(13,362)
Other (expense) income, net	(407)	1,248	482	3,132
(Loss) income before income taxes	(142,751)	77,191	(94,254)	137,498
(Benefit from) provision for income taxes	(50,470)	25,565	(38,406)	40,884
Net (loss) income	$ (92,281)	$ 51,626	$ (55,848)	$ 96,614
Net (loss) income per share:
Basic (in dollars per share)	$ (1.03)	$ 0.63	$ (0.65)	$ 1.17
Diluted (in dollars per share)	$ (1.03)	$ 0.62	$ (0.65)	$ 1.15
Weighted average shares outstanding:
Basic (in shares)	89,297	82,559	86,066	82,505
Diluted (in shares)	89,297	83,711	86,066	83,708